Do I need some kind of flexible primer on the spoiler, or sand it down to the rubber and shoot base and clear directly on top of that? I painted about 2 years ago and I've got a lot of cracking that goes all the way through the primer, so it looks like the original primer I used failed on the flexible soft material. I've got some flex add for the clear, but I didn't know if I was going to run into problems painting the basecoat directly on the rubber.

Anyone done this, what did you use?