No expertise claimed here, but I'll offer a couple of ideas for consideration.
I saw a billboard offering trailers or small houses preinstalled on barges, in southern Louisiana, where the arrangement makes a _lot_ more sense than the usual dwellings found there. I don't think I've actually seen one in use.
The more common technique for building in flood-prone areas there post-Katrina is to perch a normal house on top of an array of telephone poles, which makes the entrance stairs rather daunting, and forget about ADA compliance. A house on a barge surrounded by poles would not look sillier. I'd assume there are code issues, and especially HOA issues, either way.
I'd be inclined to put up a fixed landborne shed, basically for the sole purpose of supporting the utility weatherhead and the meter. This kind of thing is commonly done at marinas and trailer parks, so there must be a way to work out the downstream stuff that's code compliant.
Shore power connections for yachts use a few standard twist-locks or derivatives thereof, equipped with some weatherproofing. They aren't intended to be pulled apart, but it can be done, and as they age, it gets much easier, which is a source of some complaint among yacht people. They are available with voltage and current ratings high enough to supply a reasonable house or a small factory.
"Shore power" connections for travel trailers use one of two standardized blade style plugs that can be pulled apart, since they are retained only by friction. The bad news is that there are only two current ratings, 30A and I think 50A, and I think both are 115 volts only.
Or, you could just securely tie the meter box to your pylon, and use ordinary cable to connect it to your distribution panel, securely tied to the house, and route the cable so that the barge's buoyancy would cause the cable to fail in tension as the water rose.
Or, you could securely tie, etc., and leave a long drip loop in the cable between pole-borne meter box and houseboat-borne distribution box, letting the loop 'roll' as the house rose and fell between the pylons without necessarily losing electrical power just because of the transient presence of a few feet of water.
The drip loop would still fail in tension as the water lifted the barge above the pylons, but at that point you could just engage the transfer switch and run the house through an inverter from the DC output of the array of large outboard motors you'd need to control the barge's movements....
Mike Halloran
Pembroke Pines, FL, USA