I farm in the north, where a "hut" is essential.
There are numerous reasons why. You'll need sufficent room to load, suspend or handle shell stock and hold tremendous amounts of treated water. These can make small boats unstable, especially in bad weather. Sunlight can dry out tissues and rainwater can poison them. You'll also need storage for equipment, tools, chemicals, cleaners, power generators and pumps. Likewise an area for the crew to prepare and eat food, clean up and go when nature calls, if you know what I mean. Containment and treatment of discharges are paramount as to not pollute or otherwise needlessly propagate invasive or detrimental species.
Most farms build floats from what is locally available for the best price. Some countries use bamboo, concrete, wood or steel. I prefer galvanized steel over armoured foam billets for it's strength, economy and portability. Much of what I have is salvaged from other marine operations, namely fish farms.
Pilings are extremely expensive. Somewhere around $3000 US for each (more if the tug and barge has to travel to remote areas), so it won't be long before you racked up alot of money. They are also permanent, so if you decide to relocate for whatever reason, you'll be abandoning an expensive structure. The taxes and maintenance on permanent structures are also very high.