A really good question, but I would guess that the DES would look at panels mounted on a dock in the same manner that they look at canopies; they could only be used seasonally and must not obstruct a neighbors view. If you did have to remove them for winter it kinda defeats the whole purpose in regard to winter security and being able to maintain dock circulators during a sketchy ice power outage.
If however it were somehow possible
bi-facial panels would work great in this application because they would gain a very significant amount of backside power from the reflection off the water.