I am thinking of 5 square miles...per County Seat. Two square miles for everything else...
That seems like alot to "salvage" from old warehouse and such...look at Victoria TX for example. I am not seeing alot of chain link on Google Earth, although it can be hard to see I know.
If the consensus is that it shouldn't be a problem...then that solves most of my problem.
I tend to be too realistic in my games...so if I cant figure it out in real life then I usually dont let it go in game.