Wes,
Here is an O-54 yard done with Atlas track. You would need a RealTrax adapter, then a 1/2 Gargraves or other tubular track, then the Atlas track can mate with that.
This is 14 inches by 8 feet. You get three spurs with this... not bad.

This one is with O-72, the length of the switch is what causes the extra space between the lines... I think I like the O-54 more, personally.
This is 16 inches by 8 feet.

The Atlas track would need to be ballasted, but you don't have to be particular about the sloping side of the ballast as this would be a yard and you could just make the ballast level (it typically is in a yard).