[Conor Ryan]

I have a few ideas:
Try using the primer paint for glueing PVC and Applying a coat of that, then spray paint over that. My idea is that since the primer creates a surface for the glue to bond to, why can't it create a surface for the paint to bond to?(maybe i'm wrong) If you have some sitting around you my want to try it.

Another alternative, since 800 grit sandpaper isn't the easiest thing to come by, you may want to try a Very Fine Emory Cloth/Paper or Steel Wool.