Since you tow often, you may want to check around to see if you should stay with 4.56 instead of jumping to 4.88s.
I personally think 4.56s are perfect for 37s and 4.88s are perfect for 38s. Unfortunately, I am still running my 4.56s with 38s now and its a slight bit sluggish, but hardly noticeable and there is still plenty of power through all of the gears when I need it. I still tow occasionally so I am not quite ready to go to 4.88s because I think it would keep the rpms a little too high for towing long distance, but thats just my opinion.
Here are a couple of quick gear ratio calculations for you.
For stock tires and gears;
(4.10 x 60mph x 336)/ 33.6 inches = 2460 rpm 3rd gear
2460 x 0.696 (overdrive) = 1712 rpm
For 37s and 4.56
(4.56 x 60 mph x 336)/ 37 inches = 2485 rpm 3rd gear
2485 x 0.696 (overdrive) = 1729 rpm
For 37s and 4.88
(4.88 x 60 mph x 336)/ 37 inches = 2658 rpm 3rd gear
2658 x 0.696 (overdrive) = 1850 rpm
For 38s and 4.88s
(4.88 x 60 mph x 336)/ 38 inches = 2589 rpm 3rd gear
2589 X 0.696 (overdrive) = 1802 rpm