John, I'm glad you are getting to the point of thinking about the track plan again. I remember from our personal messages you were making good headway on your wife's room first.
So it looks like the last plan (which was last August) had an aisle between the wall and one side of the layout. I have seen photographs of lots of modelers using topside creepers to access parts of layouts that are farther than arm's reach. I have also read where modelers say they use them and like them. I have never used one myself. It is certainly better than the idea of climbing up and crawling around on a layout for guys our age and older. The idea never appealed to me when I was younger, perhaps because I had to do too much crawling on the floor at work to access electronic equipment and wiring. Looking at the drawing you just posted, I'm thinking you would need narrower table top for the alcove in the upper right so you can have an aisle wider than what looks like 2 feet. Otherwise It sounds like a good idea.
If you don't get some feedback here from some modelers who have used topside creepers, I would suggest starting another topic with topside creeper pros and cons as the subject title.
I am certainly glad to see you ready to get back at it.