........I had a float tube for years that used a truck inner tube and my method was to deflate the tube just enough so the walls were not touching, which also avoided cracks from forming at a sharp bend in the rubber. Never had a problem with this method and the tubes lasted until the rubber eventually dried out ...about every 3 yrs I tossed the tube in favor of a new one. You may not have that problem with one of plastic consistency but partial deflation might also work for you, and if you have the room there is no reason not to leave it inflated so long as there is not a wide temperature range. I once had a float tube in Florida (hot!) that I put in my hatchback, went to work intending to fish that evening, came back to the car with my float tube outer cover split halfway around. Dumb, dumb and dumber!
For a few bucks I had the cover resewn.....lesson learned.
Frank Church ...who will bet one of Wolfie's shiney new nickels that Frank Jr can tell even more horrible tales of the belly boat.