another neon question

ive got 2 neon lights on my roof but it gets really hot here and the adhesive that the velcro is connected to melts and they fall. whats another way to stick them to the roof without them falling or being there perminatly?

im about to get out the duck tape.

what i did, was screw mine in, never had a problem with them at all. but you said you didn't want them to be permanent.