Not sure I can help much, as I am firmly in the Ford camp, and not too familiar with Chevys. If it helps, I tow with a V-10 Ford gasser with a 3:73 rear, and it tows and controls the 11,000# 5er with ease.
2003 Ford F-350 V-10 Crew Cab 4WD Long Bed
2004 Jayco Designer Medallion 29 RLTS 5th wheel
Bill, Gayle, and Mindi (dachshund)
Retired at last !
Nothing is foolproof to a sufficiently talented fool.