I am using Thermo-Tec in my gas powered Cap232 , where I run a tuned pipe inside the wooden fuse.
I have just wrapped the entire pipe, and you can always touch it with yuor hands.
It is not very light though, and I suspect you can use some heavy fiberglass cloth with similar results.

I also have a sq.yard of Nomex that is aluminized on one side. It is used for firemens clothing, welding blankets,
and other fireshielding. Think this would be nice stuff to use on my jet.

Lars