Welcome to the forum. I hope gabby is a pet, and not someone born in Malta. Not sure how I'd take being called a "little fat".
I hate to bring this up after the fact, but the spec sheet on a 2013 m3265re is a GVWR of 16,000 lbs. I fear you may be undersized on your truck.
Please consider if the same engine and trans are used on larger, higher load/tow rated trucks it's not about the engine & trans but other components on the trucks where there are weaker points, and air bags do NOT improve ratings, they only improve the ride. This is only from someone who went through the ratings problem. Even my '06 "F350" couldn't tow that rig.