For several years, one of my background tasks has been to look for inspiration for the scene beyond the roundhouse. I took a whole lot of pictures on our cross-Canada tour in 2018, but never found exactly what I was looking for, which is a pasture with a hill. These are important to tell the story of Canadian development because Ontario was a major exporter of cheese, and that in turn was a key contributor to our economic success in the late nineteenth century.
This week, I may have found my inspiration in a photo that Barbara A White posted to Flickr. I hope she won’t mind if I embed it below; click on it to see more of her excellent photos of Renfrew county.
The only problem is the barn in the distance, although I think most pastures are close to barns, and dairy pastures would be especially so. I’ve mocked the barn up in 3mm-foot scale, and I find even with that mild compression, it brings the backdrop closer and makes the scene smaller. All the same, I think I will leave it a while to see how it ages.
Pembroke:87 
Have you considered making mockups at various scales to the original mockup (1/2 size; 1/3 size), and trying them out?
While the dimensions are difficult to guestimate, the two barns I mocked up are actually the same barn at different scales! The one on the left is 3mm/ft while the one on the right is 2mm/ft. Both are 60 ft barns.