Hi Jeff,
I like the plan. Have you used any easements in the continuous run? The now NS service area in Altoona, PA has an interesting engine service facility that would work with you area. The TT is at the end(like yours) with an engine building for diesel work.
I just fooled around with the Atlas track, switches and TT to come up with something like it and give you a ladder of stubs for storage. The diesel building is 30" long. The Atlas TT is 15º with 2 spots missing for the control house. So, I used to 081 1/3-7.5º to get to the building.
Good luck! It looks like a nice design in that space to run scale.