My dad an I drove 2 buses 1716 miles from Rexbug, ID to Union City, TN with NO PLATES and no titles, just a bill of sale. That's all the seller could provide as MCI in Anaheim had them as there was still a lien on them!
Then after we got home and spent a week an a half getting one of them ready to put in service we still had no titles. I had a trip to do and called about the titles because I still didn't have it and they told me they needed an address to "mail" it to.
I gave them the address and told them I didn't have time to wait.
And I went down to the shop, loaded my stuff and told dad I'd see him later.
Dad was like "Hey what about plates?"
I told him "They are just now sending the titles, so I have the bill of sale here. And it still has their name an DOT #'s, so I'm as good to go as we were coming home from Idaho!"
Dad immediately went to the office and called them and told them "Hey y'all need to get us some titles for these buses! My son just rolled out of here in the one bus with no plates." And told me "Don't worry dad I have the bill of sale, it has their name and DOT #'s, and that's what they told us was all we needed to drive it from ID to TN!"
They told him "hey he can't be running all over the country with our name and #'s on it!
Dad told him I already was and we would be leaving it that way until we got a title!
Strangely enough the next day we received the titles by FedEx from MCI in Anaheim.
Which meant they hadn't paid the lien off until they found out I was driving around using their name and DOT #'s!
So while I suggest you do all YOU CAN, to male it legal before rolling with it. I also want to point out most likely you'll be fine with it being an RV, having dated, & notarized title and bill of sale and some kind of plate registered to YOU!