If you havn't got enough room at 4" , that seems odd. There are several guys in my club running 35's on TJ's with 4" of lift and no body lift.
But anyways, the whole idea of a comp cut is so you can move the axle back a few inches - which means that the fuel tank needs to be replaced with an in jeep fuel cell or one of Genrights special tanks which are back from the axle.
Personally I think comp cuts with 35's and the axle in the stock location will look pretty silly, and won't give you much additional space.
But, leaving all that asside and keeping the stock tank, I'd move the filler to the top of the fenderwell facing up.