WA Resident Buying Used in AZ

Has anyone on the forum, that is a WA state resident, purchased a new/used class A motorhome from AZ and registered it in WA? Specifically, how does the sales tax/registration work? We're real close to pulling the trigger on a coach from a private party and I haven't had time to call the WA DMV (which I dread given the circuitous phone options and seemingly lack of competence these days).

I found a few related scenarios for buying/registering in other states...but not AZ to WA.

If anyone has recently done such a transaction, I would like to hear how it went. I'm told WA will credit the sales tax amount paid in AZ...but wondering about any other hidden costs buying out of state will involve.

Thanks