Just a question on how to secure triangular gussets.

Through trial and error I've discovered several ways whether it be weights or clamps to securely glue one piece of balsa wood to another.

However one activity I haven't yet figured out is how to secure a triangular gusset. Say for instance you have just secured your firewall to the fuselage side, at this point you cut and glue in the triangular stick on the back side of the firewall to ensure it is very well attached to the fuselage side. No matter how I try and pin it clamp it or weigh it down I can never get a perfect bond between both the firewall and the fuselage at the same time without standing there for 30 minutes holding it like a dufus.

I am using five minute epoxy for firewall joints and probond for the other bulkheads.

How do you guys get a perfect bond???

Please note I can't use cyno for allergy reasons.

Thanks,
Grackle