We did it with an Airstream for a couple of years, after selling our SF condo and outfitting the Airstream for working remotely (there were a couple of articles about it at the time).
Now we have it parked next to a small cottage on an island (using it as a home office). Once you shift modes like that and make the emotional / behavioral adjustments to clutter reduction (which is cathartic), tiny houses are easy and enjoyable to live with.
When you’re mobile, the notion of “your space” expands to include the outside world wherever you are. If you’re doing it right (scenic state / national parks, BLM land, etc. and avoiding parking lots — or RV parks that look like them), it’s pretty terrific.
If we were to do it again, we’d get a Sprinter conversion, and plan for a using it a few weeks/months at a time, not permanent. Once you shift your expectations a little, you really open up your options.
Check out the family behind Mali Mish, and what they manage to do with 3 kids.