Where are you located? The mountains, Nebraska flatlands, Missouri hills? I can't see being scared of the 3. 42's, myself. With the horse and torque of the new trucks, it will be able to haul what you need. My old first gen tows upwards of 30,000 gross, pulls hay out of hayfields, loads of cows out of pastures, and lugs pulling trucks out of infields. It chases cows, horses, and deer. All with 3. 55's, 265 tires, and for quite a while it had 33" tires. All with a getrag, and about 240 RWHP, and 600 ft lbs of torque. Many times I went across Iowa at 28,000# in OD, cruise on at 72 mph, and run with KW's, Pete's, and Freightshakers up the many hills. 10-12MPG loaded. Not any different then what the hotshotter is getting with his new 6. 7 loaded up.
Now, if you tell me you are in the mountains of Colorado, Wyoming, and such, then the 3. 73's would be better. Or maybe Illinios where the speed limit for trucks and trailers is 55 mph.
Whatever you get just use low range when starting loads off the beaten path, and 1st when hooked to the trailer on the street.
Michael