Your 2007 Dodge Ram 2500 QC Longbed 4X4 with 3:73
GVWR-----8800#
FAWR-----5200#
RAWR-----6010# (Important ranting)
5th wheel
GVWR--------10,500#
DRY weight-- 8791#
DRY Pin ---- 1390# 16% of dry weight---which is a low pin weight for 5th wheel)
So using 20% of GVWR----wet pin of 2100#
2100# plus 150# hitch .......2250#
RAWR...6000# minus wet pin/hitch====3750# left on RAWR
Base weight roughly 2800....leaves 950# for stuff/people etc (not all will go to rear axle of truck)
SO that trailer should be OK
(You will be over trucks GVWR when hitched up but that is NOT a legal issue...Truck MFG warranty issue/registration issue
Stay at/under AXLE Ratings/Tire Load Ranting and you will be legal)