First the disclaimer:
Every state is different, every person is different, every situation is different.
We bought our two coaches from private out of state sellers. Both times the sellers owed money to a financial institution. In one case, the seller owed considerable more than what I was buying their coach for.
I used my credit union and the sellers bank (they held the title) to transfer money into a escrow account. Once the sellers paid their bank the difference between the owed amount and the selling price, the sellers bank had the seller come in and sign the title over to me, and the bank mailed me the title.
I checked with my DMV about tags. They informed me to simply drive the motorhome from the sellers house to mine using the sellers tags. Then I had the sheriff drive out to my house, check all of the things he had to check (VIN number and a few safety items) then I went to the county clerk's office to officially transfer the coach to me and got my tags. I mailed the sellers tags back to the seller as per agreement.
Good Luck, Be Safe and Above All, Don't Forget To Have Fun
2006 Fleetwood Discovery 35H, 2014 Honda CR-V, M&G Engineering Braking System