Liking the B44.1 shell mate
Quick word regards plasticote, you should be fine with it being solvent based, not as perishable as WB gear if left out in the elements by accident...
What I tend to do after the backing has fully cured I scribe round the window masks to break the paint seal, I just do it with a blunt scalpel blade I use for picking out the LM... Doesn't need much pressure
When spraying the backing coat, as Ian mentioned do a few drop coats with the plasticote to build it up, don't do it as one full 'wet' coat or it's game over. Oooh and after spraying turn the can upside down & just give it a quick squirt - Helps prevent blockages.
MikeP