I bought a white kayak for duck hunting…

I’ve washed it thoroughly and sanded it down with 60 grit. I sprayed a small area with some flat rustoleum 2x and even though I only let it dry for about a day, I wasn’t too pleased with the adhesion. I’m not sold on how good I think the rattle can primer would improve adhesion so I thought that if I’m going to prime it, I want to make sure it’s worthwhile. Can anyone suggest any type of primer or adhesive promoter? I even thought about using some of that purple pvc adhesive. Any thoughts? I just don’t want to have to respray it all the time…