Annie your New Haven 0-6-0s are great switchers. The Boston and Maine had a similar model, but I can't remember what they are. They were neighbors and competitors but were also owned by a single owner twice in their existence. Sadly, both are gone today after pillaging and mergers in the last century.
Here's the static B&M 0-6-0 switcher on display in Lowell, MA. A piano student of mine restored this locomotive.
R.a0072735f11ee7212c28700e80b85725 (750×563) (bing.com)
This is similar to your New Haven models you have.
The White Shore can be fun to operate.
On my merger, the two ends serve as part of a through line with short passenger trains and a few longer freights that pass through on their way to other places.
I too replaced the trees with RMMs. The billboard trees look like cardboard cutouts in both TRS19 and TRS22.