Agree with popupcamping. Need some more numbers. As far as the Expy, I have an 06 with tow package and here are the ratings:
Front Gross Axle Weight Rating: 3275 lbs. FGAWR
Gross Vehicle Weigth Ratiing: 7300 lbs. GVWR
Rear Gross Axle Weight Rating: 4328 lbs. RGAWR
Wheel Base: 119"
Tow Rating: 8600 lbs.
GCWR: 15000 lbs.
HItch Rating:
Weight Carrying: 6,000# Trailer Wt. 600# Tongue Wt
Weight Distibuting: 8950# Trailer Wt. 895# Tongue Wt.
I don't know about the dual cam but it looks like you could stand to put a little more weight on the front axle of the truck which would raise the rear end of it.