Rustoleum Bed Liner Spray on Tonneau Covers?

Has anyone every tried using Rustoleum bed liner spray on Fiberglass or Gelcoat? I wanna spray my tonneau cover with a durable paint and was curious if id work. I've also heard that you have to use a undercoat spray prior to the Bed liner spray.

If you have painted your tonneau cover what have you tried and how were your results?

 

That stuff blows. Do you self a favor a get some Monstaliner or equivalent

 

I thought undercoat sprays were supposed to stay kind of soft and tacky and never fully cure.

Has anybody tried herculiner topped with exterior spar urethane (to add UV resistance)? Monstaliner looks good but it's pretty expensive.

 

I wouldn't use an undercoating spray, they tend to be more rubbery and don't give a nice looking finish. The bed liner stuff is ok, not the best but it does well enough and is easy to touch up.

 

Yeah I've used undercoat and it's junk what else is out there that I can use as a good roll on or spray paint