
My initial thoughts are that a fold out ramp would be needed, side windows, and a raised roof - not as tall as a Gown Van or Ice Cream Van, but to give adequate headroom. Straps / clamps for the chair are simple, but a seat belt with suitable anchorages would be needed. I don't know whether there are any regulations to which we would have to adhere, but obviously I'd find out if no-one here can help.
If it's possible to make such a vehicle the advantages are obvious - but then I'm sure that I don't have to list them for this forum

So, any thoughts or advice please. It's a serious question and not something to be undetaken lightly, but it could still be fun to make.