In general tongue weight should be 7%-10% of the total load (boat fully rigged with gear and fuel, and trailer). Lower than that, and you get that fishtail effect (which is very dangerous).
Dry weight from the Parker site wouldn't give you that number. You would have to add the weight of the engine, fuel, rigging, trailer, etc. Maybe someone with those models will have already calculated the weight of their rigged boat on the trailer from which you could do the calculation.
I've estimated that the weight of my 2510 with twin F-115s, fully fueled and loaded with gear on the trailer is about 8,200 lbs. My tongue weight is now about 600 lbs. She tracks nicely without any sway.