Vince - Ya got me thinking now. I had completely thrown out the idea of using ceramic insulation due to the cost and have used some foil backed stuff from Juliano's inside and on the floor and firewall - but this has rekindled my interest. Nice thing about this concoction is you can use whatever color you want, and I may consider the underside of the floorboards since I have yet to prime or paint them (they will be epoxyed regardless). Since I've been long away from model airplanes have no idea where to buy micro-ballon spheres. Do you have a good source? Keep us up to date.
How are you making out with the 1/4" Volara foam? The small piece of 3/8" neoprene that I got with my Volara makes a LOT good sanding blocks.