Its sad that you have to think this way. Have you always lived in that sort of neighborhood? If you ever get out you won't believe how different you'll feel.
All of your ideas for camouflage and hiding are great, but if you are outside with them it shouldn't matter. Aren't you worried about them trying to come inside the house?
I don't like the chainlink privacy fencing. You can still see through it and its not good for your torts to rub against, if you ever build a ground level tort enclosure. I prefer block walls, but wood or vinyl is cheaper.
I love the idea of cactus and or prickly bushes outside the fence. This definitely keeps the snoopers and opportunists away.
Prevention is always good, but I'd get prepared for what seems to be an inevitable confrontation, given your description of your neighborhood. I've got 3 big, protection trained dogs and a little one too. Two of them are national champions at the hardest protection sport in the world. Mine never bothered the torts and they did a great job of cleaning up the tortie poo.
If you don't like or want dogs, how about a nice 12 guage and some classes for how and when to properly use it. Mine solved a few problems for me during the L.A. riots a few years back.
