Non-AZ resident, can we register a fiver in AZ? Should we?

A simple way is to call Arizona DMV and ask. A lot of time you get opinions on RV forum instead of fact. I know in my case (different states involved) I needed to register where my trailer was at or it was a violation. I keep my trailer up North and it will never see Kansas. I called the DMV in MN and talked to my local DMV in KS to make sure I was in compliance. MN sends the renewal to my address in KS.