PH180 is great- they've gone up in price a bit but if you can find them in the $125 range it's a good deal. Great circuit protection, IMO much better than the 135w brick. My layout is very similar to yours in size about 17 x 8(width varies at the ends to the middle from 7.75-9). Outer loop is manly fastrack with 4 o72 curves and 12 o60 curves(so one o72 and 3 o60s in each corner), small transition section of realtrax for an o42 turnout crossover, one wireless command control o72 fastrack turnout, one remote command(controlled via ASC) o72 fastrack controller. The realtrax switch is powered by an accessory transformer, the fastrack switches by track power due to how they operate electronically(I believe a small DC motor).
But it appears you're mainly worried about power and command control.
My command control/power set-up is as followsNOTE- BPC allows you to switch what power source powers which block, i.e. I can power my entire layout with the 2 180 watt bricks, switch the inner and outer loop power source, etc....)
Outer loop Power flow(Block 1 on BPC): 2 180w PHs ----->Legacy 360w PM------(in-line fuse of 7.5 to 10 amps)--->BPC1, B1--(in-line fuse 7.5 to 10 amps)---->MTH 24 port terminal(with a TVS between 2 input ports)----> 5 or 6 feeders
----Yard power flow(Block 3 on BPC): same as above until feeders---> B3 hot to track section in yard....ground wire from MTH 24 port terminal to yard
Inner loop Power flow(Block 2 on BPC): 2 135w PHs----->TPC 300-----(in-line fuse 7.5-10amp)---->BPC1, B@---(in-line fuse 7.5-10amp)----->mth 12 port terminal(with a TVS between 2 input ports)---->3 or 4 feeders
Command set-up(ONLY in regards to TMCC base, Legacy Base, TIU): Note- if you can't tell from above, TIU is in passive mode with aux power source. I still have a TVS on each output because I never bothered to take them off after switching to passive
Y-cable/PDI connections: Legacy base y cable to A.) TMCC base 1 B.) Multiple modules, one of which is a SER2 with MTH TIU to TMCC cable
Signal to Port connections: TMCC base 1 to Legacy base via Y cable, Legacy base "one wire" to one DCS Ground output terminal then each ground output terminal connected so each DCS ground output is also a source of the Legacy/TMCC signal. DCS fixed 2 to 24 port board, DCS fixed 1 to 12 port terminal board- carrying all command signals to the terminal ports.
The multiple in-line fuses are unnecessary BUT I get added peace of mind from it. All signal strength is great, all power is great. If there's a short on a loop, the fuse between the Legacy PM and BPC or TPC and BPC is what will blow. Before I had the Legacy PM, the in-line fuse would blow much more quickly on even a minor short, the Legacy PM's current fold back feature is really neat and works.
In terms of what I am able to run(or the max that I have run): 4 to 5 Legacy locos(either two freight MUs with 3 and 2 locos MU'ed per consist or one passenger and one freight with 2 and 3 locos respectively) on my outer loop. The Passenger cars are usually 21" Atlas Horizons or K-line Superliners/heritage Amtrak- so I guess all LED. Inner loop 2 or 3 locos in an MU with freight consist. Yard 1 loco on for switching(little 0-6-0 Beth Steel switcher)
Hope that helps a bit with your concerns. Sorry I don't have the actual amperage draw