We met a couple that travelled with their son who spent most of his time in a hospital bed. They had purchased a used Greyhound bus that already had a full size lift on it, and converted it to a motorhome for themselves. That may be more than you want to take on, but it worked very well for them. I've also seen used Ryder/Budget style van trucks with lift gates converted, but again it requires a complete modification into a motorhome. As suggested above, a smaller bumper pull toyhauler might be your best bet to modify to your needs. We use a 5th wheel, and my girlfriend uses a wheelchair full time, but I can lift her easily and put her in the truck, bed, shower, etc. She has had MS for 38 years, but mostly pushes a manual wheelchair. I modified a Burr Handy lift to access the trailer, but sometimes I just pick her up and carry her in to the couch.