Could I give one serious suggestion, since you're not quite close to done?
Raise up half of the board that has 'Mechs on it to at least 1 level (1/2 inch), and another 1/4th of the board past that to a full 2 levels (1 inch). Otherwise, you're obscuring the rear-ward 'Mechs from full view, dismissing them from attention.
Example, my MUCH smaller diorama I made recently (just two companies fighting):
The reason it has hills in the back is to break up the field of view, as well as letting me put some 'Mechs back there without hiding them completely. Though that Archer on the lv2 hill is still... well... easy to miss. Maybe I should put the Atlas on there...
Just a thought. Otherwise, I LOVE the idea of making displays that allow people to look at our stuff and ooh-ahh!