There is a reason that many people have problem using glues on fuselages. The preferred resin been used as over the years in constructing fuselages is Epoxy.Compared to polyester it is a far superior resin in strengths and many other reason too numerous to describe. However, there are particularities that can be frustrating when trying to bond on to an epoxy laminate.Many products will bond to the surfaces but will eventually fail over time and will delaminate.
In the Composite industry there are rules, you can bond with epoxy on a polyester laminates however you can not bond with polyester on an epoxy laminate.This is chemistry and far too complicated to explain.GG and other similar products will work great when used on a fuselage in polyester. The complication is to ID the type of product that has been used with you fuselage, polyester or epoxy.
This is the reason why I use epoxy 90 percent of the time.