I'm back in action, after a full day of work just on the six piece sleeper.
I wanted to be sure, so I soaked the entire sleeper in oven cleaner for a few hours and all remnants of primer washed right off.
I then used lacquer thinner to release the glue and take the entire sleeper apart. I did this because I was sure that the pieces could be fit a little better and I was correct. Reassembled it all, refilled some gaps and then applied Rustoleum Painter's Touch plastic compatible primer.
The cab and hood did not have any filler or grooves and the primer literally peeled right off with masking tape. They came out perfectly clean and I applied the primer to them as well today.
Tomorrow I will wet sand and fill a few tiny spots and everything should be good for the top coat.
The primer can says the best adhesion to plastic takes 5-7 days so I won't be doing top coat until the weekend again, but after what I went through I'd wait a month if that's what it said. LOL
Thanks for the tips, advice and observations everyone, it is greatly appreciated and I hope that I can be of help here in return in the very near future.