The factory literature for 2007 shows a 750 pound tongue weight for the 25' Safari SS and 860 pounds for the 25' Safari. Based upon my experience, those numbers can be low.
A Shureline scale can get you the "actual" tongue weight to help select the weight rating of the leverage bars in a weight distribution hitch. You may find that the 800 pound bars are more appropriate and if the weight is over 900 pounds, consider the 1,000 pound bars.
The other part of the equation is the stiffness of the GMC rear springs.
See if the selling dealer will allow you to swap out the bars if the first choice is inappropriate.
WBCCI Life Member 5123, AIR 70341, 4CU, WD9EMC
TV - 2012 Dodge 2500 4x4 Cummins HO, automatic, Centramatics, Kelderman level ride airbag suspension, bed shell
2014 31' Classic model 30 twin beds, 50 amp service, 900 watt solar system, Centramatics, Dill TPMS, disc brakes, 16" tires & wheels