
Before heading south to NZ last month I tricked out my main boat. My main boat is now a big, old Llama, after nearly a decade of mostly middle-sized Yak paddling.
Before you read any farther, I warn you: this post is not about a packraft for running the occasional Class IV. If that's all you are interested in is Class III, maybe the occasional Class IV, then this stuff below likely doesn't really apply. The stock Alpacka boats are pretty much all you need.
But if you've got the adenaline itch......read on! These mods are the best I've used.
Earlier descriptions provide details on my boat mods as motivated by Tim Johnson, with help from Epic Eric Parsons and Tracy Harmon at Alaska Raft and Kayak. Here I'll briefly describe how the mods performed on my trip to New Zealand and Fiji last month.
Besides me in the black-decked Llama, six other people paddled three other packrafts, each with thigh straps. One boat was my old red Yak with its side-opening, '08 deck and another was an orange-deck, center-opening yellow Llama. All three of the boats I brought had thigh-straps and seats moved forward. Five different people, including Erik Tomsen, who might have some pertinent comments (Erik?) paddled these three boats. The last boat, a blue Yak, had its seat in the stock position and thigh straps (one person -- Tim Johnson -- comments Tim?).
My personal stats using these mods from Jan 6 -- Feb 3 in Fiji (briefly) and NZ (longer) are these:
15 runs = 2 class II runs + 6 class III runs + 7 class IV runs
2 first descents (Sabine and Upper S. Fork Mokihinui)
5 roadside runs, 1 helo run, 9 walk-in runs
~70 hours on water packrafting (but not always “pack rafting” -- packrafting is a style of boating; pack rafting is carrying your pack on a raft)
~65 hours raft packing (walking-in)
6 non-motorized boat trips = 5-day hike and raft trip (Landsborough) + 4-day hike and raft trip (Nelson Lakes NP) + 3-day hike and raft trip (Mokihinui) + 2 over-night hike and raft trips (Arahura, Taipo) + 1 day-long hike and raft trip (Oparara)
7 motorized boat trips (1 river boat, 1 helicopter, 5 automobile)
8 You-Tube videos
To begin with, the bigger boat is much more stable in bigger water as well as in radical, low-volume rapids than the smaller Yak is -- but without the mods this Super-Llama has, I'd be slopping around in the boat and/or hitting my bum on rocks, and/or bander-snatching like crazy. A Llama, for me, without something to keep me in place, is stable but harder to control. Thigh straps and the moved seat make the big boat super maneuverable.
Here are the mods:
First are the thigh straps.
These pull me forward off the stock placement of the seat, so I fixed that seat problem with Epic Eric's sewing and solved some other problems.
Tim Johnson, too, gets pulled off his seat, but hasn't fixed the problem. Consequently, Tim hit his butt so hard that he walked a bunch of rapids on the Arahura, rapids that wonky ole' me RAN, not 'cause I was more skilled, but just 'cause I was un-bruised.
It's probable that putting in thigh straps is going to be a big point of inertia for most Alpacka users and a still smaller subset will actually cut their seat out and move it forward -- which is really too bad.
Fat thigh straps and a more centered seat pretty much end bandersnatching dismounts. Watch some of the NZ videos on YouTube (Arahura where Tim has thighstraps but has not moved seat and Landsborough, Taipo, Oparara, Nelson Lakes, and Mokinihui where seats are moved in all boats and all boats have thigh straps) and see how many flip over backwards. Very rare now, with sideways upsets now being more common. That's because of thighstraps.
BTW, the thigh straps in three boats I used as demos in NZ (used by five people on many different rivers and trips of hours to days) all wound up with substantial wear in the FEET AREA. Holes developed there because the hard hiking-shoe soles hit rocks and the feet wearing the shoes are forced more downward onto the floor of the boat by the thigh straps. I got more wear there at the feet in each of the three boats in a month of paddling than in the butt sections over the multi-year life of the three boats.

Second most important mod was the seat cut free and now velcroed in. Yes I glued 2-inch wide velcro to the seat and to the boat and now the seat moves and comes out. Makes it better for drying when it comes out and for repairs.
Third, I have a big, beefy back rest, also with velcro holding it in place. I reckon that my backrest is the same size and dimensions as an Explorer seat. The boat is now supremely comfy. No numb legs, super back support, and super control and stability. Sometimes when I look at it it looks as inviting as a sofa-lounge chair.

Fourth, I glued some "strap plates" onto the bottom of the boat about between my knees and strap the BEST SIZED DRY BAG (15 L) right there with a strap. Oh my, does that make the boat feel like a dreamy, fantasy rock shoe (snug and fitting with control and no pain)! With thigh straps and that drybag full of overnight gear I am set for backcountry Class IV. The boat is much more nimble than with weight on the bow. The weight is centered by the center of gravity. SWEET!

Fifth is for FIVE INCHES of VELCRO on a center opening spray deck. I get out fine (thank you) when upside down underwater with thigh straps, the mondo-velcro and the drybag. This is the second secret to a dry boat (the first is be smart about where and how you paddle in whitewater); the third secret is listed below.
Sixth is the bi-modal "fun-rail". More experienced boaters than I had commented/warned on the danger of foot entrapment on the full fun-rail. So, even though I had glued on a total of ten tie downs, I cut two off (the ones where my hands paddle) and now just use the four in front and the four in the back for 1/4 inch polypro line that doesn't go around the mid section of the boat (just the bow and stern -- four patches in both places -- check the photos). I find this really useful to grab onto so I don't get flushed away from my boat and have now, in real combat situations, towed swimmers with the rear rail. I thought I'd miss the mid-line rail, but do not miss it at all; however, having chicken line on bow and stern seems necessary to me now.

Seventh is the third secret to a really dry boat: two sleeves/pockets with velcro closures on either side of the center closing velcro at the top of the skirt. Each pocket holds a partially inflated 2 L Platypus bag, although any plastic stiffener would likely work. This is simply awesome. Oh what's that I hear? the water dam on your spray deck is dependent on the PFD you use? Yes, that's true, so...
....while not boat mods, if you are wanting to stay dry in whitewater consider a "two piece" whitewater LJ (i.e. life jacket), the kind with front and back foam but connected without side foam. Then wear it so the front foam is high and you will have an amazingly dry boat. Also, if you want to paddle white water Class IV, then get a stiff kayak paddle. People I have paddled with who have a 4-piece "packraft paddle" (like Aqua-bound) and a ONE-PIECE Werner (or other glass/carbon fiber) kayak paddle find that the "real" kayak paddle so much better that they are willing to carry in the one piece instead. Let me reiterate that: they have the choice of paddles and even for a multi-day trip of walking they bring the real paddle after using the Aqubound paddle in whitewater.
Again, if you are just paddling Class III and the occasional IV and are a basher and a smasher, stick with the Aqua-bound; if you are easy on stuff and paddling Class II/III, go with the Sawyer. But if you want to get hooked on the white stuff get a real paddle (4 piece, short one), a real whitewater helmet (not a bike or adventure racing helmet), some elbow pads, some swiftwater rescue training, then paddle with tolerant kayakers and get after it.
Be careful. The addiction is hard to kick.