[Turk]

Duane,
You let Carroll put his finger prints all over your dash?
It will help authenticate the signature at a later date.
DNA may be helpful too. I may have some around here, and let me give you some.

I had him sign the glove box door on mine. It makes it easier to replace, or to clean around.

My guess any of the vinyl cleaners without petroleum base, should do fine when it comes to cleaning the dash. He usually signs with permanent Silver Ink.
You could run a test yourself and see what attacks it, what doesn't.

TURK