Which do you want more...another line for train or command operations?
I see having to tie on to the mountain top in the first photo. The r-loop will mess up the amusement park. Next will be the coaling tower and support scene and the beacon tower.
I would use a pylon style support between the tracks on the way to the next corner. Then, a tower there will need a new home.
Finally, the corner on the transformer table near the wall looks like easy pickin's.
Command operations will necessitate the addition of a Lionel-Lock-on Building for each track or a PSX-AC for fast action circuit protection for the electronics. I suppose that you could get a ZW-C or ZW-L.
It's not just the #990, but the power and control upgrades that will add to the cost.
I would go for the additional line and save command for another layout.
The balloon reverse looks like it takes up too much space. I wanted to see if it would work. (see attached)