I'd rake the submerged weed growth to shore as much as possible, then get a bobcat and push the top layer of clay/plants off to another location to compost out. Lay down the geotex and cover with sand. Plan on adding more sand in the future. On the edges of the sand beach I'd border it off with some rock over the geotex too. That way you can contain spreading/creeping plants. You'll get some fish beds in that sand at some point
If I can do it with the bucket of my tractor maybe. Still on a tight budget.
