Have you seen the High-top vans being sold today? They are not crazy priced, and could easily be set up as a teeny tiny house on wheels....
I'm considering buying one next time to outfit as a very temporary RV from which to camp for two days and go fishing...You could put a rug on the floor, a cot, a cooler and a porta potty, and a 50 gallon plastic water container and you'd be set....Plenty of room. Thye make so much neat camping stuff today...for one person, it'd be fine.
The Nissan NV, or Ford or Dodge all look like great choices. I could see it.
On the day that I Took delivery of my jeep wrangler from the Jeep dealer there was a guy buying one of those tall Dodge vans.
He told me that he was going to convert the van into a camping van and live in it for extended periods of time while traveling with his wife.
Having a newer vehicle definitely would be nice for better reliability and fuel economy.