Propane Manifold is to big

So I managed to use one of the legs of my stand for a propane manifold which looks and works great, the only down side is it left me with about 20 inch's of dead space that I would like to fill after seeing how long my pilot lights stay lit once the valve is shut off.

I was thinking about filling the space with this :

http://www.grainger.com/Grainger/SUREBOND-Silicone-Sealant-4FFF8

What do people think, the wasted propane is not much of a concern to me as the amount or propane left in the manifold in the event that I needed to shut it off in an emergency.

Sorry forgot to upload a couple pics so that it makes more sense.

Two things to consider:

- silicon caulk is usually (maybe even always) air cured. If you fill an enclosed space, all of the caulk that is not exposed to air will remain in the same gooey form as it was in the cartridge.

- you might want to read the MSDS sheet for this stuff.

Cheers!