I'll trow down 2 cents of short wheelbase towin' info, though it has no bearing on the trans...sorry...
Back in the day, I lived @ 2k ft elevation, a few miles from the ocean. Towing an 18' Bayliner with a 350 volvo penta outdrive (chev) down to the boat ramp, with a Toyota 4WD pickup can get REAL interesting coming down a relatively steep curve in the road. Let's just say that the big heavy boat wanted to go straight, trying it's best to push the rear of the tow rig into a drift/roll scenario.
Y'know how hard it is to convince your right foot to hammer the skinny pedal @ that moment in time?
I'm just glad I had it in 4-Hi.