If there's one thing that's common in large AT-AT sets, it's wasted space. Built to spec, they have far less troop seating than they should. I recently posted modifications I made to 4483 to deal with that, but I was never fully satisfied with those.
Here, by getting rid of the brick-built "comfy chair" seats, I have made the side trays able to hold five troopers (whether they be snowtroopers or regular stormtroopers) each. And by hinging the side panels at the top to allow access, I was able to add a 2x10 plate (seats four troopers in this case... well, if the rearmost are snowtroopers they'll have to stand, but still) to either side.