This is sort of an obvious suggestion and might sound like overkill, but I personally would consider consulting two different auto/plane professional painters, even if only to look at the primer situation (i.e. find out why the topcoat is coming off, and for suggestions on a suitable topcoat for the current primer).
I fell pray to the Stits Smoothprime/Flight Gloss fiasco, what a mess. Talk about topcoat peeling off......
Painting a plane is obviously a big undertaking, something that you don't want to do twice. Moreover, you'd hate to have problems in a couple years that you might have been able to avoid by having skilled eyes look at things now.