Sparky, I am not a detailer and don't have a fiberglass boat. However, I've used duragloss 501 marine polish on white
fleet cars. It is extremely chemical resistant. You can even mix it with duraglos 601 at the time of application and make it more durable. However, this product has cleaning/polishing properties and gets a little gunky on pads and with your boat freshly polished you may not need the cleaning properties.
Although not labeled as a marine wax, if your boat is fully polished I would also consider jescar powerlock. It goes on and comes off so easy that you may be willing to use it more often. It is also chemical resistant ( as in touch free wash chemicals)
Also look at collinite waxes-again, I'm assuming chemical resistance=durability