[DanEC]

The body does need to be firmly mounted before that work, and hopefully in such a way that it can be mounted back exactly as before if it needs to be removed for painting. I like 3/16” gaps for bare fiberglass but depending on thickness of the glass and the swing action of the hinges as the two panels swing past one another, it could need to be a little wider. If the glass is pretty thick, I’ve sanded the back edge of the inside of the door skin on the hinge side to a bevel to provide more clearance. I also radius all panel edges slightly so to provide a bit more clearance and to hold paint better. A bare fiberglass gap of 3/16” will end up as little as 1/8” once all primer and paint are applied which is actually pretty tight.