Re: longer hitch for launching boat
To answer the question of "why such heavy tongue weights?"
Easy... tongue weight should be 10% or MORE of the weight of the all-up package of boat and trailer.
I'm at #2950 for the boat, probably #1000 for the trailer (minimum), without any extra gear. So Figure #3950... 10% is 395lbs, and the tongue is every bit of that, if not slightly more. THAT'S why such heavy tongue weight! if you are less than 10% tongue weight, you have a serious unbalanced rig and should consider moving the boat forward on the trailer.
"Rum Line" an S2 7.9 - cheap, fast, trailerable, and paid for.