We towed some pretty heavy tows with our 1997 1500 4x4. 5.7 engine, bigger brakes retrofitted. This picture is of our 1968 Boles Aero 28 foot travel trailer that is kitted out as a production vehicle, capable of being fully powered and independent in wilderness situations (along with being a SHTF bug out vehicle, loaded for bear with a good years of all needed supplies.....(we even got ac to work off our solar panels which cover the entire roof, with 8 6volt deep cycle batteries, and a 10,000watt 110v power inverter) When towing this, once to montana and back, we weighed at a CAT station a combined weight )suburban, trailer, all of us in it) at 16,400 pounds! The stupid weak point of course was the 4L60E transmission, which we had the cooling tube extra large pan, three oil cooler radiators in the front of all the other radiators, and of course having to take it reeealllly slow up steep grades.... We went up Sherman Pass in the High sierras, the whole way in 4low, watching the trans oil temp gauge like a hawk! It the trailer hadn't of had high performance dual axle dual system brakes (both electric and fluid) we would have never towed with it.... as it was, if we would hit the trailer brakes at highway speeds, it would slow the whole rig down very fast.
Towed great, but when we accelerated from a stop, you could literally feel the entire suburban flex and hunker. We heavy towed that trailer over the years for about a total of 30,000 miles. With that tranny however, it really was not fun(went through 4 trannys, in the space of 3 years, Aamco warrantied 3 of them), like going up the grapevine in the emergency shoulder, doing 6 mph.....:Wow1: no more heavy towing that rig until we get ahold of a 2500.... sometime possibly in the future.
Oh, and our 97 sub, with 35 inch tires, got about 10mpg 11 if we were lucky, and while towing that huge travel trailer, we got 8.5-9 mpg