Yes, putting PA tags on an unregistered vehicle IS a very bad idea.

VWofA should be able to give you a letter or compliance. You will need to
make a couple minor changesto the vehicle to meet DOT requirements BEFORE
bringing the vehicle across the border, and those changes will be spelled
out in your compliance letter.

For one thing, you will need the former owner's title and/or registration
(if from Quebec, registration only is required as they have no vehicle
"title" as a separate form). The former registration is required by
Pennsylvania Bureau of Motor Vehicles before they will issue you a new
title and registration. You will also need to submit to the state the
proper documentation you will receive from US Customs when you cross the
border and pay your duty.

Duty on passenger vehicles is 2.5% and duty on trucks is 25% (the crewcab
is considered a truck).

Good luck.

Michael J Vickey