Full-time, eyes open

Less than a mortgage in an expensive city, more than the internet suggests, and the range is enormous depending on how you travel. The line items people leave out are the ones that get them: fuel at single-digit miles per gallon, insurance on a vehicle that is also a house, maintenance on that vehicle under constant load, and the repair that puts you in a motel for a week. Site fees are the cost you control most, which is why free camping matters so much to the math.

Domicile is the state you are legally a resident of when you have no fixed address, and it determines your taxes, vehicle registration, insurance rates, voting, and jury duty. It is not the same as where you happen to be parked. Full-timers converge on a small number of states for reasons that are mostly about income tax, registration cost, and having a mail service the state recognizes. It is worth choosing deliberately rather than by accident.

Through a mail forwarding service, which gives you a real street address, scans your mail, and sends physical items to wherever you will be. It is a solved problem and it is one of the first things to set up, because your domicile choice and your mail service are tangled together: some states require an address of a type that only certain services provide.

This is the hardest unglamorous problem in full-timing, because health insurance networks are geographic and you are not. A plan that is excellent in your domicile state can be out of network everywhere you actually are. People solve it in different ways, none of them elegant, and it is worth researching properly before you sell the house rather than after.

Yes, and it is the single biggest lever you have. A developed campground runs roughly $38 a night on average, which is well over $1,000 a month if you always pay for a site. Full-timers who are set up to camp comfortably on public land spend a fraction of that. The catch is that free camping demands water and power self-sufficiency, which is capital cost up front.