On Friday, March 16, 2018 at 6:20:38 AM UTC-5, wrote:
If you have a good Dive Shop in the area and go in and explain what you are trying to do they might be about to modify a BC (buoyancy compensator) that you could sit on and then inflate to lift up. They certainly will have bottles of different sizes, small ones used to emergency air could be your air source. May be a bit of a stretch, but if you have a good shop could be worth the conversation time spent.

Kevin
92

what about a lawn tractor inner tube with the valve core removed and a can of tire inflator (without any sealer) might cost less than $50 and be small and portable.