Yes, you guessed it. I used some old proseal to glue the tip on. This was especially need for the aft end of the tip, see photo 2 below. You can kink of see the aluminum puffs away from the tip and there are not any rivets down in this area because the space is too skinny for shop heads on the inside.
So I applied proseal and riveted it together. Then I clamped it. I let it stand for days and when clamps were removed it was really stuck together.
PS, Vans told me the expiration date on proseal is just a guideline. It does become thicker with age, but it will still set up. I would not use old proseal for sealing the fuel tanks. But as a thick glue it is okay.