Sorry, I didn't realize the picture was from another post.
Drilling a 1/2" hole through the middle of the cross supports will certainly kill its function.
Is that false bottom made by Bobby? If so, maybe he can weld you one with one of the cross members at an offset, giving your diptube the needed space. That support cross doesn't have to be exactly centered to do its job. If in doubt, a double strip, one on each side of the diptube, would make it even stronger.
Are you saying there's a tri-clamp fitting on the
inside of the kettle attaching to the diptube?
Are these double bottoms supposed to be used without
any legs? How big is that span?
I think I would have one leg in the center cross, at minimum. And in your case, under the off-center cross if you can get one.