I can't really help you with your question but is the 9,000 GVWR you mentioned the total towing capacity of the truck or is that the GVWR of the Grey Wolf. You will need to know both.
IMHO from past experience, you do not want the GVWR of the RV to go beyond around 65 to 75% of the total towing capacity of the truck. If you go beyond that, you may find yourself under powered at times especially if you plan on doing any traveling in hilly/mountain terrain.
Also be sure you have the towing package on the truck (proper gear ratios, oil coolers, stronger suspension, etc.). If you don't, at least add a transmission fluid cooler or you may find yourself sitting on the side of the road somewhere (speaking from experience with prior TV, even with fluid cooler on the towing package).
Anyway, welcome to the forum.