We towed our 22 Cruiser, which was very close to 5000 pounds trailered on the scale, with a 2000 Suburban. It was the 4 x 4 version, 3.73 if I remember correctly, and 5.3 V-8. I believe the towing capacity was 7200 and we were well within the GCWR.
The Suburban towed VERY well and felt safe...