They're going to make great structure, but I have to assume they'll be laying flat on the pond basin, and not standing upright as you had indicated you'd like some of them to.
If my assumption is correct, I think they would be best utilized in 4-5' of water. That's not to say that they couldn't do great in 7' of water, but depending on the type of fishing you'll do, sometimes you can't the lures down that low.
