Dawn dish soap will strip the wax right off fiberglass. That’s what I wash the boat with before reapplying wax.
The Works and other toilet bowl cleaners are good for hard water spots on the metal portions of the motor, transom, and tilt-trim.
A 3 gallon bucket of very warm water, boat soap, and about two cups of white vinegar is the standard go-to for cleaning the boat. I bet by doubling or tripling the vinegar content, it would take this right off.