Most insurance companies require a physical address where an RV or any other vehicle is based, also called a "garage address." This is because they based their premiums based on where the vehicle is primarily used as well as Homeland Security regulations implemented since 9/11. It's one reason I purchased a lot in a co-op RV park when I retired. It came in handy as a place to retreat during the extended Covid lockdown but otherwise I'm only there briefly each year. It's my legal address for domicile purposes like banking, voting, taxes, vehicle registration, insurance, etc.
Escapees have traditionally been able to offer domicile in Livingston, Tx to their mail service customers after winning a voting rights case on their behalf. The win was based on Escapees only offering mail forwarding to their members and their headquarters and mail forwarding service being co-located with a large campground available to any Escapees member. But this may be changing based on the recent sale of the club minus the park system and mail service.