I think the best car for this adventure would be a motorcycle. I would look for a 1999-2000 Honda Goldwing. In terms of comfort, it is like a couch on wheels. You will have to pack light, especially if you want to camp out, but all you really need is two sets of clothes each with a spare pair of shorts, an extra t-shirt, and a pair of flip flops for each of you to wear when you do laundry every few days. Try to find one with luggage racks on top of the trunk and on top of the saddle bags so you can strap bags on top of them.
If you have never ridden a motorcycle before, I suggest you both start by enrolling in the Motorcycle Safety Foundation’s Basic Rider’s Course and take it together. By the time the course is over, you will know if motorcycling is for you.