My wife is an L1 para with use of her quadriceps. She can handle our 5.4 mR Searider with standard jockey console just fine. About a week ago I had a mid-T's para with no leg function whatsoever out on the boat for an afternoon. He boarded without assistance from a dock level with the top of the tubes, transferred to the jockey seat and held on to the grab lines. He absolutely loved the boat, was interested in buying a RIB after spending the day blasting around. He and his wife had been looking at pontoon boats and other worthless scrap, but loved the ride of the rib in the 10-15 knot breeze and related chop. He an I were the most secure when I underestimated the size of some powerboat wake and nearly got the rib airborne
During the course of the week of training, several of the paraplegic crew transferred off their sailboats to the coach's Zodiac POS and were scooting around the practice area while seated on the bench seat, while the coach took their place on the sailboat. It's really up to the ability of the individual and the conditions. I would be disinclined to put someone aboard in their chair.