How do people who live in their motorhomes determine their state of residence?

I’m having one of those “let’s sell the house, buy a motorhome, pack up the cats and live like vagabonds” kind of days.

This has led me to wonder how those people determine their residence for things like taxes and insurance and banking. Do they just choose the residence of a trusted family member or friend and hope that they keep track of any important mail?

Do any of you know someone who has done this? How did they handle these things?