I launch & retrieve my 14,000 lb rig with the '4WD Lo' enabled, but not sure I really need it. . . just easier not to have to set it while on the ramp. Off-road tires are your friend
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This ramp is shallow, and there is a steeper ramp a few miles down the road that probably would need 4WD Lo and a few prayers to go along with it (sandy concrete
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Given that your boat is, well, a bit heavier than the truck is rated for, using 4-LOW is highly recommended, it reduces the strain on the auto trans by virture of the much lower gear ratio overall and that reduces the amount of torque converter slip necessary to get started.
When driving off road in the beach sand out on Long Island we do the same thing with all 3 Jeeps. Two are automatics, one is a standard shift, all benefit from LOW range starting off in the sand, and on hills, because on Jeeps 4 low gives you an addition reduction of 2.73:1 overall gear ratio. The automatics can start off with very little torque converter slip and the standard shift Wrangler, very little clutch slip needed in fact it can start in 2nd gear on flat areas, 1st on hills.
While my 07 Grand with the 5.7 doesn't need low range to pull out our small boat, if I towed it with the Wrangler 6 spd I for sure would use it to reduce strain on the clutch. If I had to pull it out with old '98 4.0 liter six I'd use 4 LOW just out of deference to the age of the drivetrain. It does have a big trans cooler fitted.