I am not sure the tire tube would reach all the way into the tapered front end of the float. I finally got my hands on some polyurethane film and have some sample material coming from a manufacturer. Polyurethane is VERY tough and durable, heat welds flawlessly, and stretches enough to fill small voids. This will be the perfect bladder material. The next float will be as good or better than commercially available floats, I think. It will definitely be cheaper and custom. I'll keep everyone posted.