Aptar-
You seem to be buying additional parts from other manufacturers to solve your problem. You need to go directly to JMP and get the items you need. It would be money well spent. You are just going to keep spending good money after bad and get marginal results if any.
I agree with several others on this post in that I've never seen a JMP T-33 with any heat problem in the aft end of the aircraft. Trying to use a ceramic insulator is just going to add weight with minimal results when the proper designed components will make all your problems go away.

Now go do the right thing.

Marty O