My uncle, who is retired from VA state police, told me to do this when I bought a car in NY and wanted to drive it to Florida:

Make sure you don't have any outstanding warrants

Get proof of insurance with the VIN of the new vehicle on it from your insurance company.

Get registration paperwork from your state, fill it out and have it with you.

Make sure the vehicle is in good condition as far as lights, tires, etc.

Take a piece of cardboard, cut it size of license plate, write NO TAG on it neatly and put it where rear plate goes on vehicle.

Have all your transfer paperwork in order.

Dress nice

Take off

Drive properly

He said most cops could care less about writing a ticket for not having a tag - not a moving violation in most states - if everything else is in order.  Putting a NO TAG sign on the car is telling the truth, not like using a tag off another vehicle.  Insurance is the bigger deal.

Cops know what a pain some states make it to get temporary tags.

I've done this on several occasions.  I've never gotten pulled but have been passed by the police.

Joe/Albuquerque