A question before the wish - is there any reason that large urban areas, like those around strats now, couldn't be used at tank town areas?
Simple answer....yes there is. I tried this with my MA terrain, using sections of the city as GV clutter on spawn routes and in tank town. Unfortunately these tiles are tied into the strat system in a way that can't be got round so HTC made me get rid of them. MA terrain builders are not allowed to add custom shapes to their terrains either. So the only clutter you can use is the "tanktown" object that's used in at least one MA terrain now.
I would like to see HTC make a few custom groups of buildings for MA terrains. They could use existing building objects to create new villages, towns, factories, bridges etc. These would not have to have any strategic purpose, they could just be for visual effect and to give GVs something to fight in besides countryside.