Okay, so I tried sealing two gaskets together on the old cap.
I took the gaskets out of the caps. I bought an old version of the cap, and even brand new it came pre lubed with oil on the back side. I cleaned the gaskets up with some brake cleaner.
I used high temp liquid gasket on one surface, but left room at the edge of the gasket for the cap lip to grap on to. Yes, that's Hondabond.
Then I mate the surfaces. Some liquid seeped to the inside as I pressed the surfaces together. I just wiped it aroud the inside and cleaned off the excess.
Then I put the double gasket in teh old cap. I put the outside edge in first and made sure teh cap lip grabbed the bottom gasket. Be sure you get the bottom gasket to be grabbed complete around the circumference. You'll notice that the inside edge buldges up. That is because the top gasket is getting pushed by the cap lip.
I used a digital caliper measured the distance from the cap arm to the gasket flush agains the cap. it is 2.77mm.
I lube the gasket surface and the vanos surface, and I put the cap on carefully so that the gasket doesn't buldge up or detach (since it is still wet).
I take it off to check, and the gaskets are still properly adhesed together. I put the cap back on. And now I am waiting for the liquid gasket to dry.