Arnold - this is a fun topic! I also want to acknowledge with you that you're not alone with limited real estate. I do have room for 36", though, so I am able to look at some medium locos. One of the primary benefits of Lionel trains is the ability to turn in a small area, while having big trains. If you have room for 72" curves you have room for 2-rail O. But what I wanted to share was my "low profile" access to the water main for the house. It is held in place with gravity (the wedge at bottom) and magnets along the sides. Takes less than half an inch to pull away from the magnets and lift up for access. (And yes, I tunneled through the wall!)
