Marc,

Bit tricky to see how the tank lines up with the turbine? Is the rear of the tank level with the exit cone? The front part of the turbine won't get that hot so get the tank as far forward as poss. Maybe move the turbine back a little if it hasn't been mounted yet?

But as Sandor said, BVM heatproof paint and/or cermaic blanket should work OK but I would look to move the tank entirely if it is underneath the tailcone.

Rgds,
Mark