Hi Lewis, thanks for your interest in the packrafts!
I’m not aware of anyone making a traditional multi-chamber inflatable from one of my designs yet, but it shouldn’t be too difficult. It’s a bit more work to seal off different sections of the tubes, but it can be done. If you cut the side tube in half and add an extra-wide seam there, you’ll have an inward-facing TPU surface you can heat seal a circular bulkhead to.
A simpler method is to have separate cylindrical drybags that you insert into the tubes through the airtight zipper before inflating the packraft. These can be made of lighter fabric (40D), or the same fabric as the tubes (210D), depending on whether weight or durability is most important to you.
You can also make an inflatable floor insert, which acts as an additional chamber, along with your seat.
Cheers