Thanks for the responses. I assume GM states max pin weight at 3100 even though the max payload is 3700 simply to give a little room for stuff that is going to be in the truck regardless. Fuel, Driver, etc.
I bought this truck thinking it would easily tow any 5er we would want. Well I didn't realize the floor plans we both want turned out to be 40+ feet long. Looking at luxury models in that length I am seeing GCWs in the 16,000 range. To error on the side of caution I'm taking 20% of the GCW for a theoretical "max" pin weight. But that's putting some of them at 3200 or better depending on model. Now I don't think she and I would ever max out any RV. It's just me and her and 2 dogs. No kids etc. I have had two TT previously and I doubt I ever had 1,000 pounds of stuff in either of them.
All that being said I don't want to do something stupid and put us and others at risk on the road. Am I being to cautious or what? I'm only talking a couple hundred lbs. either way. Not like I'm wanting to hitch to something with a 5,000lb pin weight.