Is there not a good house site on the opposite side of the lake? How long has the dam been there, has it been tested with several back to back super heavy rains ? Have you had a engineer look at it?
Your concern is redimix trucks but there will be other trucks just as heavy. A load of drywall, framing and a bunch of osb could weigh as much as a load of concrete. Then no one knows the future. Lota $ and risk


"Why do you ask"?

Too many people spend money they don't have , on things they don't need, to impress people they don't know.