Oh I understand what You're saying Richard. The brand I used was CUTEX, it contains acetone which is the stuff that would harm plastic. I don't want to make a blanket statement that this will work on all tampo print, but it did work for me. I'll say this, I was prepared to repaint the doors minimally, so I guess it was kind of a risk that just happened to pay off. Right now I'm working on a 1/18 scale '68 Cougar that had a vinyl top, that is actually only flat black painted on. Again using that same CUTEX to remove it. and it's not hurting the blue paint underneath.
I also bought a 1969 Boss 302 from this same manufacturer. It was painted in a Bud Moore Trans Am team car scheme. I also removed tampoed numbers and added Parnelli Jones' number. I can post pictures of that some time.