I would suggest going larger. First with girls that age, you may be taking friends in the future, so more room the better. You may also decide you want to upgrade to a larger camper and if so you will be able to easily. Finally as a previous poster mentioned, longer (and heavier) is better for towing. I have a 28' bunk house (6000# loaded), towing with my son's CC Z71 (5.3), short tows are ok on flat land, but tiring to do. Towing with my 3/4 ton Ext. Cab(6.0), much more relaxing and using my father-in-laws new dually mega cab cummins, very easy, but...
That said, I would consider the Suburban, then either the Expedition or Tahoe over the Dodge, just for the bigger frame and longer wheel base. If you get the Dodge, then the Hemi again more weight and power.
