Why not just use prop kind of bricks rather than any old brick?
Like the decorative brick pack, or the trash can and soda machine bricks, those sort of things. Just have those lieing all over the build and use the models for a playertype, if that's possible.
Also, another idea- In case people memorize the build and thus know what is and isn't a player 100% of the time, maybe the build can have a lot of invisible bricks and props that randomize which ones are visible each round.
Although I guess that can just be evented and doesn't need to be a function of the gamemode