So I'm building a N scale layout of a shortline that's in the Appalachia mountains. The longest piece of equipment I'll have on the route is the 4-6-0 steam locomotive and the Harriman Passenger cars. Both of which I measured out to be 5" long. Now originally I thought that the minimum radius I'd be able to run was 18". This is probably still true, but I'm also wondering if I could also go to a smaller radius. Any suggestions?