My DH and I are FIRE and we full-time in an RV (a small class A). Right now we're in Imperial Dam LTVA on the CA/AZ border, boondocking in comfort due to our solar panels.
To all the doubters, let me tell you, go to any LTVA during the winter months in this area and you will see people full-time (or snowbird) in ALL KINDS OF SETUPS!! It's fabulous and inspiring to see. One of the best things about being out here is taking walks and "spying on the neighbors" as I like to call it, i.e. checking out everyone's setup. There are tiny truck campers, class B's, class C's, class A's, tiny trailers, toy haulers, huge fifth wheels, bus conversions (from short school bus to giant touring bus), even tenters.
We do a lot of boondocking, and at other times we travel more conventionally by staying in RV parks and state/county/city/national parks. It's kind of fun to do things differently when boondocking, and after a while conserving water like crazy becomes second nature. Let me tell you, if everyone in the country used as little water as DH and I (and this includes showers and dishes and all the normal things), we wouldn't have water water shortages anywhere.
It's the mindset, just like in anything else. Live in a truck camper because you need to and you resent it? You won't have a good time. Live in a truck camper because you are FIRE and want to see the continent? Awesome.
OP, if you have the desire, just do it. You know best what you can tolerate. Those Sprinter vans tend to have good resale value if you decide in a few years that you want something different. The only non-negotiable I would say is you should have at least one good solar panel on the roof. It makes life so much easier, and quieter because you hardly ever need to run the generator.