I've got a plan for a 4x11 I built (HO). If that's your scale and IF there's any chance of squeaking another foot, let me know... BUT I'll warn you that - having actually built this one - there is NO reasonable way to cut it to 4x10. It's spaghetti bowl and just too tight - I knocked it down from 4x15 myself and there's not one more 1/2 inch of give in it, much less a full foot...
Sorry, HO Scale, I could probally squeeze another 1 or so. I was think of modeling a small coal loading area and some mountains, no grades, because I don't know how to make them. Small town and a small station. Thanks