Rugdude,
Welcome to TDP, you won't find better Duramax information anyplace.
Don't be afraid to ask questions, TDP members very friendly have an incredible amount of knowledge.
I agree with a5150nut and DmaxMaverick. You need a duly to safely tow a 38' trailer.
I have a 38' Forest River, Sandpiper, 5th wheel and I tow it with a CCDRW 2006 Duramax Silverado. My truck does just fine towing the 38' 5th wheel, but on a windy day it can still get pushed around pretty good even with the dual wheels. A 2500HD, short bed, SRW truck will definitely be a hand full with a 38' 5th wheel on the back. I also suggest that you check the weight rating on the factory tires after you load up the trailer and get the axle weights from a certified scale.
I am not being negative about your plans, I just want to see you enjoy your travels and return home safe. I love traveling and I am sure that you will also.
Good luck
John
*2006 Chevy, 3500, 4X4, DRW, (LBZ) D/A, CC, LT, 252K Miles, 19.5" Wheels, Mag Hytec Transmission Pan and Differential Cover, SS Grill Guard, Racor 2 micron aux fuel filter, 100 Gallon Aux Fuel Tank, using Edge Evolution, Predator Diablosport, Kennedy ECM tune, Fitch Fuel Catalyst.
*2006 Four Winds, Dutchman, 36', RV, D/A, 5500 Kodiak.
*1993 Harley Davidson, Turbo charged, Springer Softail.
*2007 Pontiac Solstice.
*2005 Jeep, Liberty, CRD (diesel).
*Full-timing in USA, see America first.
BUY AMERICAN or CANADIAN, NOTHING from CHINA .