One idea you might consider is digging a channel inland a bit and build your dock/boathouse around it. The wave action diminishes the further inland you go. I had noticed a moat at a base near the sea had minimal water level changes when the nearby ocean was going bonkers. I dug a channel a few Karve lengths inland and the water level at the end had much reduced fluctuation during storms. People on the forum confirmed this 'feature'.
Digging a few test holes could give you some gauge of the effect.