@gunrunnerjohn posted:AAMOF, I don't know how you'd do that with off the shelf switches with any O-scale track system.
Not that it's practical but an Atlas #7.5 switch and an O36 1/4 curve yields less than 2.5" center rail to center rail spacing or a #5 switch and O54 half-curve yields ~ 2.75" center rail to center rail spacing or an O54 switch and an O27 half-curve will give you a 3" center rail to center rail spacing.
-Greg