Capnmorgan asked about wheelchair houseboaters on the old forum. I can't respond to that thread, so I thought I would start a new one to share what limited knowledge I have.
My wife has been in a wheelchair for almost 19 years. We had a 28ft pontoon houseboat when she had her accident, and after having the deck gates and the front door widen, we realized that was one form of entertainment we could still continue.
We've tried a few other houseboats since then and some worked better than others. We tried an old Stardust houseboat that was split level. Wheelchairs don't do well with split level. I made an 8' ramp to wheel her down to the lower level, but it wasn't very convenient.
Our latest boat is a 58' Playcraft single level pontoon houseboat. We had to take out a couple of closets to make the hallway wider and widen the bathroom door, and those modifications give her access to most of the boat. Of course, the top deck is not accessible. I would like to get some sort of elevator or crane to hoist her topside, but that gets pretty expensive.
The other thing you need to watch for is accessibility of the dock. The lakes in Arkansas are often surrounded by hills and sometimes there just isn't a practical way to make ramp down to the water level.