There is a facebook group; "Rubber Tramp Art Community" I don't know how active they are. I would imagine of the people who travel around and set up at Art Festivals/Shows/etc. there must be some who live out of their vehicles.
I'm going full time at the end of May and will be painting based out of my van. I have a french easel and a table I can set up outside. I'll be doing some Plein air painting and continuing some series of work started in the studio. I don't paint beautiful ideal places in an idealized manner as most plein air painters do. Its already been done so well by so many it seems a bit futile to me. (although when I have done it in the past I was able to sell most of my output. People seem to want it)
I'm going to be looking to buy some property in about a year in Northern New Mexico. I'm thinking about establishing a studio there and finding the right way to market my work in the area, which already has an established art market. Will be spending at least a year living out of my van, fishing, hiking, painting, visiting friends, enjoying whatever I can, and scouting out potential locations to set up a home base/studio.
Plein Air Painting is a popular past time with many folks. I imagine there are groups you could meet up with. Probably some live nomadically at least some of the time to be able to be in locations they want to paint. In researching web sites and You Tube videos doing my van build I came across a number of people who were building out vans to go on painting trips. You might try making inquiries through painting groups as well as through nomad channels?