I am actually already building some PVC trees (waiting on marine epoxy to cure to hold the limbs in place), and I've nearly got a small wall of cinder blocks stacked in the garage waiting to be dumped as well. I'm also planning a rather unique structure consisting mainly of 4x4 beams and some spare latticework, I'll have to send in pictures to PondBoss when it's done...
As far as other homeowners, my neighbor and I are the only ones who fish really, couple people will bank-fish from the dam now and then but really it's practically "my" lake as long as what I do doesn't attract the wrong sort of attention.
What I'm considering doing with the PVC trees is putting them just off the flat on the high side of a slope where it goes from being 4-8' to 12-14', but I was really thinking of putting the "reef" in deeper water, at least around the 14-16' area. After reading the above advice, I do have a remaining question, and that is how much (if at all) will the thermocline layer depth move from season to season?