i thought at one time I saw Walthers rear of building facades, like just the rear of merchants row but can't seem to be able to find them again. Looking for flat or close to flat rear of commercial buildings for edge of layout, with the building rears facing staging yard and maybe a warehouse as well. I did see some of the ITLA warehouse options. Thanks.
Downtown Deco has a warehouse flat. These structures are not plastic or styrene, but made from Hydrocal, I believe.
https://downtown-deco.myshopify.com/products/shipping-wearhouse-flat-dd2010
Scott
Take a look at this site. Lots of good stuff.
https://www.tracksideflats.com/n-scale
Rich
Alton Junction
You can also scratch build what you want. My examples are HO scale but N scale shouldn't be much more difficult.
I have also made computer designed and printed building flats using the Evan Designs Model Builder software. I've used this software to make 3D N scale buildings, too.
Finally, I have photographed the backs of 3D buildings (the sides you can't see from the aisle) and used the printed photos as background flats. If you want a little more depth to the photos, mount them on foam core board before placing them on the layout.
Hornblower