Here’s a pretty rough idea for now…
Bombsite 2 would remain where it currently was. Bombsite 1 would be moved to a sub level, where the exact location would be completely dependent on the layout of that area. The existing location of Bombsite 1 would be a fairly exposed double escalator granting access to the sub-floor. There would be another entrance next to the PDA mid-escalator, and perhaps a small drop ladder in the right hand area. I would also have a means of more direct access to the sub-area from somewhere closer to the defensive spawn too (maybe the stair-well). I have no idea how the sub-level layout might look, but I can see separating the two objectives like this allowing for defenders to become less separated by all the large objects in this area and being able to set up better crossfires.
I marked out some potential 5v5 positions that would allow defenders to have good crossfires on all of the entrances and easily be able to rotate between the objectives and one another. It might be that some upper level openings would need to be blocked off; probably just with glass so that you can still see where an attack is coming from. Note: The PDA opening I would close off with clear glass that you can’t shoot through, and the window on the left would be identical to that on the right (that you can shoot through). Anyway this is just one idea for now, and I’ll probably add some other completely different ideas later on.