If you are truly limited to 4' "It is what it is". But a few inches could make big changes. Namely what I would prefer, is a second crossover/turnout set, and/or a second reverse loop. But that makes for spaghetti.
I rolled with the 0-31 in most spots for now.
An el for your "critter" line?. Real nice if its a trolley.
(Have to keep you thinking
)
"As is", your engine overhang might be hitting walls, so I tightened it, but only slightly. What engines you will buy and run, is key to your turns and spacing here. Bigger is better. Overhang, and kick-out between trains in parallel curves is wider than parallel straights.
The offset gap can take scenery to separate the 2 lines from being a "racetrack".
Going "over size" on 8' you could do it more scenery too.
Or something like this?
