Yes it's not too thick so should work well. I've used both products extensively on the Roadster and have had no problems whatsoever. You could also stick Relect-a-Cool over the tunnel on the inside, then have the matting over that.
The MGBV8 came with reflective foil stuck over the tunnel as standard, and although it's counter-intuitive seeing the silver facing away from the heat source, it did seem to help.
