More On That Cake tin

I've been doing some drawing, & here's what the cake tin mentioned yesterday will become.

Having cut the boot lid out, there's nothing to support the fuel filler, so I designed a bracket to hold the filler just below the boot lid surface, but that would let the rain in yes? well the cake tin will become a "splash bowl" around the filler & will have a drain to the outside under the car somewhere. Like this:-