The differentiation between an RV and a (park model) mobile home has nothing to do with being self propelled here. It really comes down to whether HUD certifies it as a dwelling. I found all of this out when my SIL bought a "tiny home" before tiny homes were cool. He was a park ranger and they didn't have kids so his home was as portable as his job. It made it a lot easier to work his way up through the bureaucracy. If a better job opened, he could move at a moment's notice.