Something is weird because I have 285/75/16 procomp AT on mine with just a 3.5 spindle lift in the front. I have 3.55 LS and I have no problem pulling my 19ft boat.. even got it stuck in the muud a few weeks back and with a little help pulled it out.. 2wd 4.6L

Not sure why you would have problems..

 

that is strange put it in 4low like the others said and did you air down your tires.

 

Gears would help you tow better for sure, but it does sound like you've got other problems.

 

I really don't think airing down the tires would help at all. The problem isn't that he can't get traction, it's that the engine bogs down. By airing down the tires, he'd just have underinflated tires that still aren't getting power to them.