I don't have have a barn. I do have a full basement on a medium sized house and I have a decent 2 rail layout. A lot of 2 rail stuff will operate on 48 inch radius curves including all 40-50 ft freight cars in my opinon. I have a small fleet of GGD 2 rail passenger cars which replaced a large fleet of Walthers built up 2 rail passenger cars (from kits). All will handle my 52 inch minimum radius with ease (my branch is 48 inch radius).
I mikados, pacifics and mountains a couple 10 drivered locos that handle the curves pretty well. The Max Grey 2-10-4 does complains but still runs.
So I want to disagree that you need "40 acres" for a 2 rail layout and that you can't get along without traction tires in O Scale.
By the way the grades on my mainline are 1.5 % or less which is NOT a steep grade.
Until you learn about 2 rail O scale and try it, you should not tell people what does not work.
