This last weekend I added two small pallet structures, placed an 8' long piece of old steel gas delivery pipe to the top of the log cabin to help hold it down, and wired the solitary logs down to keep them from floating away. I had been kind of worried about this last task, but with simple tools, #9 steel wire, and used 15"&18" guard rail bolts for stakes, it was really easy. The bottom of my other pond (in basically the same soil) is firm enough to hold such stakes, so hopefully this'll work okay too.
Typical log wiring job:
The North SMB bed area, perhaps final configuration:

.
The South beds, ditto: