Buying a motorhome in a different state for a full timer

One of the key things I would suggest is keep good documentation. Know the laws of a state, such as CA for residency. It is up to you to prove your residence, including in another state if you stay more than XX days in a state, and compliance to state laws. It may even require you to prove you were not in the state more than XX days, such as gas receipts where you filled up in another state.