KRM,
yeah, it's tough with photos sometimes to find a reference for sizing. I used Lionel O27. O54 curves. A loop would takes less space than the balloon. O72 may take over the end tables. Take a tape measure and add 3 1/4" to the diameter of the curve, although the O27 uses the outside rail and the O the center rail. See what it hides.
I just tried to get a shape to see how it would fit. I noticed the space with the bridge...Just didn't put it in for a mock-up
I see it as mostly on elevated trestles or sub-roadbed and under girder looking detail.
I wouldn't hide what you have with a full deck. maybe along the walls with small land mass in the corners and trestles for 1/4-1/3 of the r-loop.
Look at photos and see what you like. The more open look is more work, but well worth it in my opinion.
The 10amp breakers are too big and slow for command engine electronics. (in my opinion) The PW#91 are nice, but hard to find. They are 6 amp magnetic, adjustable to less.
