Missed your new member status....but welcome to the forum.
Your a brave person for coming on a rv website and mention a 1500 truck pulling a 5th wheel trailer.
For whatever reason some rv folks don't think a 1/2 ton truck can pull a 5th wheel trailer.
Anywayz give etrailer a call and be sure to include your GMC trucks ARC package. I'm sure they have other customers with trucks and ARC systems.