Bought a complete door kit, for my 51 GMC, that has a rubber deal that the wing window closes against. The sent a bunch of little rivets and a rivet punch. I can't see how you would be able to seat the rivets since the vent frame is in the way of your hammer.
I tried to spread one rivet on my anvil and it took some pretty heavy whacks.

Any tricks, tips, or ideas?

Thanks

Sidehill