I once thought about an RV as well. Probably more to turn it into a mobile musicstudio as well as a place to live. But looking at the cost of a decent RV, it costs me the same as a house... yikes.
But I don't drive, so that's not going to work anyway.
I stumbled upon this recently;
Mobile Living: The Unicat : TreeHugger
For 2 people I don't know.. but on your own... it's totally awesome.
Since I'm moving out "soon"... within the next year probably, I'm looking options and what works for me. If anything; and money would not be an issue, I'd like to have a detachted house/place with a workshop on the bottom floor and a 2 or 3 room appartment on top. That way I wouldn't have to cram my hobby stuff in a single room or shed and be short on space for both storing and working on projects.
On a more serious note though; detached or really, really, really sound proof. I'd hate to live my life with earplugs in because neighbours are noisy and/or if I can hear them going up the stairs. I need a place that's totally devoid of possible distractions. Pipes isolated enough so I can't hear running water would be a start.
Aside from a bit of practical issues... I lived my life pretty much in a 9 by 12 foot room and I don't really need a lot more space than that. I'm quite efficient with putting my stuff in here. Yes, I use a kitchen and bathroom I share with my parents, but let's include that here as a room + kitchen + bathroom by means of "living". I'm totally fine with having my "hovel" as a place where I sleep, live and maybe even eat. I do end up going in the backyard sometimes for practical reasons that I cannot use spraypaints indoors... unless I have industrial grade ventilation. But looking at it; I think a 2 room appartment would be totally fine for me. Chances are I wouldn't use the rooms as intended either. One hobby room as a sort of workshop, and one as that so called "hovel". A big practical issue I don't run into a lot right now is storage for non "me" things. We have a giant fridge in the basement and one in the shed (as well as one in the kitchen). So we're rarely "out of stock"... such things might require a bit of adapting for me to deal with a single fridge and all, but storage capacity all over in the house is based on an entire family, not a single person... quite sure I couldn't afford to fill 3 fridges on a weekly basis either, lol.
A while ago I also considered moving in with an aspie friend. We had some plans which were totally fine. Those included a "minimal" living thing where we'd have our own bedroom and a giant shared lounge, as well as throwing our instruments and gear together for a studio in the basement.
But yeah... based on how I live right now, I don't think I want it a lot different. Having a house of my own (even rented) annoys me already in terms of "heating bills" and occupying all rooms... I don't even have stuff for that many rooms, lol Nor do I want stuff for other rooms. Changes are that out or boredom I'd just put my bed in a different room each night, just to use said rooms every once in a while.