Well a standard class 3 hitch can handle a trailer of up to 5000# with 500# of tongue weight. As long as your boat, trailer and gear stowed in the boat stays under the 5000# you are safe on the hitch side.
Your manual should have a chart of what the maximum towing capacity is. This number will most likely be under the 5000# the hitch can handle but depending on trailer brakes and such can allow you to tow more.
Simply GCWR, is your Gross (total) Combined Weight Ratio, this is the total (sum) maximum weight of tow vehicle (with gear, occupants, etc) and the towed (trailer) vehicle. Stay under this number of pounds and you should be OK. Just be aware that most boat trailers have surge brakes (they are crap). And there will be a noticeable delay from when you hit the brakes and the trailer brakes apply. Kind of like the air brakes on a Transport. You need to be diligent in making sure those brakes are operating properly. If they fail you will jackknife at the worst, or find that it takes forever to stop.