Unique Ideas for Gas Cap Location??

I'm building up my 71 Demon with a trunk mounted fuel cell that will no longer use the factory fill neck / gas cap. As I do the body work now, my plan was to weld plate over the factory cap location and smooth the panel to omit the cap. Before doing that, just curious if anyone has any other creative/unique ideas of what could be hidden under the factory cap location?

Charging posts? Cutoff switch? Etc.

Thanks