One of my friends suggests that if you have a lot of backpacking gear (I do), to just get a flatbed truck and stick a truck cap on it, and live in there. Or use a minivan or larger van. Pros: Cheaper than a van conversion or RV.
I would probably want to add a couple batteries in there to run my CPAP, fridge, and other things.
Two companies do conversions for minivans — Oasis Campervans out of Colorado [1][2], and RoadLoft which makes removable "kits" [1].
Even the professional minivan builds have very limited cargo space. I would probably have to get one of those roof-rack cargo units, and put my less-valuable stuff in them.
Costs: battery bank (??), fridge ($300-2000), composting toilet?? ($1400+)
They're at the cheaper end of RVs. Cons: They rarely have a toilet/shower. Pros: They usually have electric wired up, and sometimes have a heater and A/C.
Van conversion
There are some rather posh van conversions. I just don't have the money for even the cheaper versions.
Stealth matters. Van conversions and flatbed trucks are more stealthy than school buses or RVs.
There are various stories of people who stopped doing the vanlife thing, or who examine the pros/cons in detail: [1][2][3][4]