TopH20,

you may try some vertical structure. In the past I have taken small trees (8-10 feet tall) and attached a cinder block or two to the bottom. about 2/3 the way up the tree tie in (with plastic zip ties) an old milk carton (cap on) the milk carton will float the tree/bush upright. As long as you dont put too many blocks on the bottom you can move the entire pile around while its underwater.

I have a few clients around Atlanta that cant sink structure as well. A good marker is a cheap fishing float, cant be seen from shore.

Shan O'Gorman
Professional Ponds