To illustrate what is, and isn’t possible; this is a 78” x 36” door, loco is a Lionel semi-Scale Berkshire
1) Lionel O31 Track including short straight in curve and reversing loop, it seemed to fit together better that way
2) Lionel O27 Track, O27 switches including passing loop, reversing loop and two sidings. Essentially this allows two trains to be on the layout together. It would be possible to set it up so that they alternated, stopping automatically in the passing loop, but I didn’t try that yet.
As you can see, you get a lot more operating potential with O27. Trains are basically loco plus three cars. The 24xx carriages suit it very well.
I have had a Williams die-cast Scale Hudson around this loop, but there is a tendency for the tender to derail. The “semi-Scale” version includes a shorter tender, which would make sense. Lionel and K Line semi-Scale Hudsons, the semi-Scale PE 2-8-4 and traditional-sized PW locos like the #2025 2-6-2 romp round and the 0-4-0 switcher looks good, too.
One point about electric switches - the instructions warn against leaving locos too close to them, making the contact for the solenoid and eventually, damaging the switch. I looked at electric switches and concluded that they were not appropriate, for that reason.
I also looked at O42 radius switches, and O42 easements into the curves but they just take up too much room.
