Thanks again for all the input. All of it, and yet, none of it is helpful!

Here are the priorities for what I need from the project.
1. When I look up from my desk, I want to see less blue foam.
2. When I look up from my desk, I don't want to see track hanging in space.
3. I need the open side to have the appearance of an overpass (Think of
@randgust 's highway bridge against the backdrop, or for those of you old enough to remember, the York Road underpass in Cockeysville.)
4. I need the back side of it to look like a continuation of the landscape inside the upper loop for the purposes of establishing some more structures.
5. I need it to be functional for the ridiculous menagerie of N scale equipment I, a grown-a$$ man, play with, which includes silly looking long cars, overhead electric locomotives, and impossibly tight turns.
My preferences
1. I prefer that the solution not look ridiculous
2. I prefer that the solution use parts and pieces that I have on hand
3. I prefer that the solution not create more problems than it solves.
4. I prefer that the result create a nice backdrop (or 2) as a photo location
5. I prefer that it be reasonably easy to execute to a reasonable degree of quality/reliability
So, with those things in mind, I'm moving on building the components so I can more clearly see how I'm doing on the above list.
Stay tuned for further updates.
Lee