Some use posts set in 5 gallon buckets full of concrete. Others use pipes driven into the water. Trying to drive in wood posts that float will be almost impossible. Bad enough trying to pull them down onto already set concrete footers. It was NOT easy.

After creating our smaller fixed dock, I would instead have a fixed deck on the shoreline, then a pivoting ramp out to a float dock. That way when the water level fluctuates, the dock goes with it and it wont be up in the air like an eyesore.