A related question: Are the published displacement numbers for other boats equally suspect? It looks like it wouldn't hurt to contact the builders directly just to doublecheck.
Generally speaking, published displacement weights are suspect, unless it's for a strict one-design class. Generally speaking, you can add 300-500 pounds for sails, outboard, anchors, etc for a trailerable boat, plus hundreds of pounds more for the weight of the trailer and spare tire, etc. For example, my 1985 West Wight Potter had a published displacement of 1200#, but that was laughably inaccurate. It weighed 2450# on a truck scale (including tongue weight) fully loaded for a week of cruising, without food or water.
My 24' Corsair has a published displacement of 1803#, but the race commitee for my rating certificate hoisted just the boat without the trailer on a load cell -- and it was 2515#, even when stripped down to the bare essentials - sails, cabin cushions, instruments, 5 hp outboard, empty gas tank, one small anchor and minimal rode, gear required by USCG regulations. and small tool box. With the trailer, and cruising gear, it weighs 3500 pounds on the truck scale (including tongue weight)
-So as a guesstimate, you can add 1200-1500 pounds to the published weight of the boat to get a "real" towing weight. Plus add the weight of extra gear and people in the car. Then check what the rear axle capacity is, so you don't overload it.
You may need to add a weight distribution hitch with anti sway bars for safety. You can get one made for use with surge brakes. Take a look at this 6000 pound WD hitch for boats and surge brakes. It's by Fastway, which is a subsidiary of Equalizer. You'll need a pole-tonge adaptor for the boat trailer ini addition to the weight distribution hitch.
YMMV,
Judy