Why not use the heat shield it came with? As Colin says, the heat shield only buys you some time if the fire continues to burn.
What is done on CG inspected boats is that a pull cable is attached to the shut off valve and run topside somewhere so the fuel
can be shut down remotely, limiting the amount of fuel
that can burn during a fire. This is a really good idea because it won't take long for rubber fuel hoses or the plastic bowl to burn through. Then you have a fire you can't stop by shutting down the fuel source because it is too hot to get at the fuel shut off valve at the tank.