Before building a skeena, I designed and built a packraft of my own which involved layering up two layers of approximately 250gsm fabric together. These were TPU coated on one side only, with the coated surfaces facing inwards. It did work OK except for a few wrinkles and as noted above, the laminated fabric is stiff.
I wasn’t overly happy with the final boat, hence building a skeena afterwards. 🙂