I pulled a 6500lb trailer, overall length 29ft, using a 2004 Yukon (Tahoe equiv.) with no problems. Just make sure you have the hitch, weight distribution bars, and sway control set correctly. Also, I would recommend a Prodigy brake controller. They give very good brake control and smooth application.
We could comfortably pull at 65mph on the interstate. Of note is that we got better mileage using tow/haul mode and third gear than using 4th gear. At 65mph in third the engine was right in its "sweet spot".