I've examined space available for whole thing: it will be slightly larger that proxied goliaths' base but when I place tank it might be crowdy;
I think I will make some broken walls of styto and might sprinkle some bricks if I make up effective way to make lots og them fast and izzzy
why don't you check some galleries from modelling events? Those historical modellers can do magic when it comes to dioramas, you will surely find some inspiration there.
There is my report from Bytom 2011 in the "contests" section, check the gallery of pics I made there