RV registration in SD

It wouldn't surprise me if SD was happy to collect a couple hundred a year for giving you a piece of paper that may or may not have validity. They really have nothing to lose.

But it sure sounds like you are a resident/domiciled/(pick your favorite legal term) in AZ.
- AZ likely won't be happy if they find out they didn't get their pound of flesh.
- Make sure your insurance company is fully aware and in writing of the situation. Don't be surprised if they have an issue. If you keep it from them and they find out after an accident, don't be surprised when they don't want to pay out due to fraud.

This is assuming the RV spends much of it's time in AZ and is generally stored in AZ when not in use.

If the RV never enters AZ, you might be legit but still best to check with your insurance and the AZ DMV.

Check the AZ DMV website for their requirements. A lot of states don't like local residents registering their vehicles out of state for pretty obvious reasons (revenue). Your AZ drivers license combined with SD plates might get you in hot water if you get pulled over in AZ.

Any benefits to being a Arizona resident over a SD resident?

Is your insurance company on board with an RV registered in South Dakota while garaged/parked at your new Arizona home when not traveling? Insurance companies get to charge based on risk and you don’t want to mislead them about where the RV is…domiciled. What’s the reason for not registering in your new state?

I just chatted with someone from the DOR. She said we can maintain our RV registration in SD, but not every county will allow it. The research continues.