You would be hard pressed to walk the length of a one-barrel-wide dock as depicted in your drawing, but it sure would be entertaining to watch. I think you'd be better off finding a small derelict pontoon boat, 16 or 18' for a bargain basement price. Strip off everything above the chassis, refloor it with plywood or decking, attach your trolling motor and you're golden. Rather than concrete filled buckets, Harbor Freight has 18" earth anchors, they can be screwed in to ground level so you can mow over them if needed.
