In just about every place in the world, you need a street address to register a title or get vehicle insurance.
No reason you can't get creative and use the street address of the dealership or your hotel...

Yep. But proof is pretty fluid - receipt for rent, hotel receipt. Most (all?) States require you to produce 100 points of ID, you'll have to do a websearch for the requirements in the State that you want to make the purchase.


Its best not to try and avoid that requirement, I met a French couple a few years ago who had bought a campervan from another backpacker who had not done any sort of registration change and they were the ones held up for about a week whilst it was all sorted - outstanding fines, no stamp duty paid, no valid insurance (big one), etc etc.