Thanks for the comments. It has been up a week and I haven't noticed any flexing plates, but it is very possible over time. From the screws that I have tested, they seem to be hold up well. I usually stop the train in the corners since there a bit more support there with the Lego plates.
I did consider using long plates to support the straight tracks but since the wall supports are 10 inches apart (two tracks) it would be fairly expensive to purchase long plates.
Clearing the corners was challenging for the Emerald Night, specifically for the blinders in the front as you might have noticed it was changed in the film.
I have to switch the battery on and run it for the most part, mostly be design since he is 10 months old.