Buy a new “cubby hole” lid, and drill that to take the fittings?
Retain the original cover to fit if/when you need to return the bike to standard.
Just a thought…. Personally I wouldn’t do it, but each to their own.
(Also, I don’t know how easy/difficult it would be to get hold of a new lid for the cubby hole.)
Sorry for referring to the tank recess as a cubby hole, but I don’t know what bmw called it.