I had a pool built with a ramp to allow me to push my chair in the 2 1/2 ft shallow end of the pool where I can get out of my chair and swim around. Is this chair waterproof? While I’m swimming the chair would be in about 2.5 ft of water for about 20-25min at a time. Is this chair designed to be particularly submerged for 20-30min at a time? Are there any rust concerns? Thanks