Whats better for towing - SR or OR trim?

i tow with an offroad that has the tow package.. my travel trailer is 3700 pounds empty. probably around 4300 loaded. truck pulls it fine. plenty of power for any hill so far. if you keep it at 60-65 its not all that bad but at 65-75mph the motor is screaming most of the time 4000-4500 rpm. trans seems to up and down shift constantly too. it only gets 6-9mpg while towing and that depends a lot on my speed.. the truck only has a 20 gal tank which sucks when towing and getting under 10 mpg.

the offroad has pretty soft suspension. whats the sr like? i know my sons sport is a lot more firm and i would think would be a little better to tow with...

i leased the truck so if i didn't like how it towed i wouldn't be stuck with it. glad i did.. it will be getting turned in at the end of the lease and i'm going with a full size truck with a V8 in it. gonna look at the tundra, f150/250 and the chevy,gmc 1500/2500 and see what one i like best.