Here is the difference between my 2006 and your 2007. I chose 205x75r15 LRD rather than 215 or 225 for this reason & still there is occasional rubbing on excursions
I have another plastic wheel well liner and one of my projects is to remove the original liner ad see if I can reshape the opening for a little more clearance. Think another inch would be enough, right now just have almost a finger on the street side and almost two on the curb side with a 1/2 tank of water and empty thetford and gray.
About the only other thing I could do would be to relocate the battery (70 lbs) from the far street side rear to the curb side but think reworking the wheel well will be enough since I do not drive on ungraded dirt roads.
Personally would rather radius the wheel well than add a lift kit.
Also think the ecoboost-type engine is the future of towing particularly if planning at altitude but Jeep/Ram may not get that until 2016 (a
direct injection turbo Pentastar is in the works).