Mike, my hat is off to you and your wife. Most folks with serious mobility issues would tend to stay home. Your approach is to think outside the box -- well done!
It sounds like you have the mechanical skills to make this happen, and a strong desire to succeed. A custom unit is probably the only way you can get a wide enough doorway, accessible seating and bedding, and a proper bathroom.
The only problem that I see is that your new trailer is going to be heavy, with all of that extra hardware. I am not sure a van is up to the task of towing such a big load. Is it possible to put a van type body on a truck chassis?
