A '64 GT is 19' long and the dry weight (from the factory, no options) is 2890 lbs with a tongue weight of 385 lbs. Ours when loaded for a trip is more like 3500 lbs with a tongue weight of 430 lbs. Generally speaking, the older trailers are lighter than the newer ones. So You could also look at 15'-18' models, 1964
and older as being "lighter" than a '64 GT.
If you are "borderline" on a tow vehicle...you may want to reconsider as a "remodeled or restored" trailer will most likely be heavier that the original stated weight in the chart above...ours is and we didn't change much at all.