It might be helpful to look at a lighter 5er and a little shorter. I have a used 2008 Laredo 29RL aluminum frame dry weight 7975 load capacity 2925 that puts me at 10,900
I am sure I am a little over that when the actual weight numbers are crunched, but still well under 13000 GVWR towing capacity of my 20015 GMC 2500HD. The 29RL is actually 31' to the rear ladder Plenty of room for two adults Maybe you need more room if you have a larger family If so I would reconsider the size of 2500 for what you want. You may be happier with more horses or less 5er. My Anderson hitch helps with the shorter 6.5 box and no chucking with an Anderson Ultimate Hitch...Decisions decisions life is always about decisions. Just looked at your 5er and it is definitely too much 5er for your 2500 horse.
some of the Specs on 2500 GMC HD:
Weight: 5741 lbs
Wheelbase: 133.6 in.
Engine Type: 6.0L V8
Power: 360 hp @ 5400 rpm
Torque: 380 lb-ft @ 4200 rpm
Transmission: 6-Speed Automatic
Chassis
Layout: Rear Wheel Drive
Front Suspension: Torsion-Beam
Rear Suspension: Solid Axle
Wheels
Front: 17" Steel
Front Tires: LT235/80R17
Rear: 17" Steel
Rear Tires: LT235/80R17
Trailering & Hauling
Trailer Weight: 14500 lbs
Payload: 3534