if you have winter, you could build the log platform and build the thing on the snow and ice above the pond or lake that you're building on. as everything melts it would be in the water.
also, wouldn't it being surrounded by water make maintanence on the outside of the container more difficult?
I don't see why it couldn't be done, since the sea/land containers were meant to be transported by ship or barge. If you check for-sale ads for boats, you may actually find an old barge cheap (be careful, though, as boats of any kind are notorious money pits, needing a lot of maintenance, not to mention slip costs if you don't have your own dock).
