I'm fairly new to model trains.  I just built a platform for my layout.  The platform is L-shaped, with both legs of the L being only 2 feet wide, because of limited available space.  I am looking to do a single loop around both legs of the L.  I know the 22" curves are too large.  Am I going to be okay with 18" radius track, or do I need to tear down my platform and start over with more width?

Thanks for any help I can get.