Is anyone towing their 337RLS or similar weighted FW with a 2500HD Crew Cab Standard Box (not long box)? We have the 6.6L duramax & 3.73. Our main concern is we will be bumping right up against the max GAWR for the rear axle and the GVWR for the truck. Have the truck already and it's brand new so replacing it is not an option. Do not have the 337RLS quite yet, but supposed to take delivery very shortly. Will be using Pull rite slider hitch and air bags. A little late to be realizing this, but wondering if we are setting our selves up for major issues, or if the truck can handle it. We will be towing on the (mostly) flats in Texas about 5-6 times a year.