@AviatorRuss, I tend to agree with the others that your original plan seems rather complex. Christmas tree running is typically a display style layout so simple is generally better. Covid has made some materials scarce, so start getting your foam sheets soon. Use precut woodland scenic risers if you want to save time on elevation changes. If you're looking to save on cost then cut the foam sections yourself. In the past I glued two 2" sections together, then ran them through the table saw for long straight cuts. This makes a terrible mess but the finished product was spot on.
For putting foam together I highly recommend Glidden Gripper. It's a primer paint but works amazingly well at sticking foam board together.
Also, you mentioned scenery as your weak suit. Well, right now is the time to strengthen that up. Get some foam. Glue , cut, shape, file etc. Then practice painting. There's lots of various techniques for foam painting. Dec 12th is not the day to try them for the first time.
I highly recommend a practice project. 1' wide by 2' wide is plenty. But give yourself a deadline, say anywhere from 3 to 5 weeks, and make a practice project with a couple feet of track, wiring, paint and scenery. It's now August. By the time the practice run is over it will be mid to late September. With everything that happens in the fall you will feel the desired date for your Christmas layout bearing down on you like a freight train!
If you want some inspiration from a total foam novice like I was, check out my Halloween 2017 thread. I built that layout for fun and simply so I had an excuse on how to learn about working with foam.
Have fun my man!!
