A look at a small Hornby TT scale locomotive as well as an American Flyer Baldwin Switcher S scale. These two scales are much less common in the US (although TT is popular in Europe) than HO, N, and O scale, but they might be a good scale for you if you are looking to maximize the size of the equipment you are running in the available space that you have.
►TT scale locomotive: https://uk.hornby.com/products/gbrf-class-08-0-6-0-08924-era-11-tt3003m
►S Scale Baldwin Switcher (Amazon): https://amzn.to/3V4Yr74
►Same, but from Tain World: https://www.trainworld.com/catalogsearch/result/?q=American+flyer+baldwin+switcher