I think it's like anything else. If you stay at Motel 6 versus a Hilton. How much you drive. How comfortable you want to be temperature wise, heat and a/c. Then there's maintenance, repairs and if it's a bus and a diesel, you're a trucker, you get it.
As mentioned, lots of YouTubers, including people living on the SSI. They have some incredible ways of making life comfortable and affordable.
For me, when I fully retire, the plan is to follow the moderate weather, stay put for a good amount of time and find low cost places to stay.
One retired woman stays the Summer in New Mexico. New Mexico has a deal where you can buy a season pass to all their state parks for $250. There's a limit on the amount of time you can stay in each park, but it sounds like a great way to see the state. This cuts down on her fuel, maintenance, etc. by staying put.
Sign up to be camp hosts. Free camping in return or a bit of campsite management.
Health insurance is always a big one for me. If I lived in a U.K. country, I'd really be foot loose and fancy free.
Per work, there's lots of options.
With Elon's satellite internet, it's going to easier to work remotely.
As you said, make a product and sell it. People who go to the different fairs around the country representing a product or selling their own wares.
Buy a cosmetic deprived home, live in your skoolie while you fix up the home, then sell the home. Take the profits and go buy the next home. Or, rent the home out. This way, if you keep investing in homes around the country, you can write off traveling and such expenses when you go visit the homes to check on them, do repairs, meet potential clients. A Tax person can help you figure out that part. Pretty soon, you've got investments homes around the country and get to write off going to visit them.
My main point is, there's opportunities. You have to know your abilities and how to put them to work while living on the road.
Hope some of this got some ideas flowing.
Best of luck.