How Does One Secure the Sail Panel Cardboard Inserts 64-66 Barracuda?

OMG. I just realized when I did my headliner 10 years ago...I dont think I have that backer board behind there! I must have because the light screwed in but......I remember putting some batting up there to give it some body ? I have yet to hit it with the hair dryer...10 years! How long and at what temp and distance with the hair dryer, does it really pucker up or is it very minimal? I just dont want to watch a hole burn through the headliner. Mine is black fabric with the pinholes, not vinyl