I cheated and created The Great Dales Railway. An independent concern but operated as a joint line with some LMS services. Really a pretext to have different coloured engines/r.stock. GDR are blue, the odd crimson LMS plus lots of weathered black things. Also I can, as the fattish controller, import locos from anywhere on the basis that GDR picked them up 2nd hand from elsewhere.
Scenery etc based on DerbyDales (hence my newfound knowledge of cows & sheep from elsewhere here). A BLT at Dinsdale connecting to junction at Barnestoneworth.*
So, as many on here have said, if it looks ok to you then it's ok. And if your mates come round with a few cans so they can be a signalman for an hour all the better. As long as you've got the area "feel" right, eeeeeee Bob's yer mum's brother.
*and yes B'worth United played in the Yorkshire Combination. I do know.