Another issue - crossing into Canada with temp registration?

Many years ago, I bought a couple of vehicles from California dealers. At that time, licensed dealers were agents for the CA DMV, and took care of all the title transfer and registration paperwork, as well as collecting the sales tax.
Perhaps it is different for new, never before registered vehicles, I don't know.
If it were me, I think I would go to the dealer and get the sales manager and the title clerk in the same room and find out what is going on.