Yep, don't get the auto parts store/hardware store double faced tape. go to a real body shop supply place and get the real stuff. Its also no real cheap, but you'll find lots of stuff to use it for.
1fastbrick answered you over on PT forums and I did too but no harm in duplicating the answer here in case it helps someone else, 3M VHB tape from the body/paint supply. Gray tape with the cherry red backing. It's super strong. And, use wax/grease remover prep spray on the panel first.
Richard