After some discussion and oobservations/discussions from the Vansairforce and other sites, I have decided to put some basic insultation on the Tunnel floor and to make sure that the SCAT tubes are fully sealed and no HOT air can penetrate.
In addition I have decided to apply a thin Firewall blanket to the engine side of the firewall using SS Foil, Fibrefrax Ceramic matt, stainless steel rivets and a high temp silicone sealant. I am still awaiting all of the components for the Firewall, however, I did receive the insulation.
Thermoguard 2000 is the material used for tunnel insulation and I did a fire burn test to ensure that it was not going to be a major problem. It self extinguished and low outgassing. Given it is only on the inside of the aircraft and not accessing flame directly, should be good. Just need to worry about fuel soak on Filter cleanouts.