For my first session with pro-seal, I back riveted all of the stiffeners in place. Next I installed the fuel sump and finally the filler cap. Pro-seal is nasty stuff, but not that bad to work with if you go into it prepared. I.e. have plenty of rubber gloves,MEK, and a long sleeve shirt. I have read more than once that there is no known chemical to remove this stuff. I believe it.
