The issue with a Class C that you might need to consider are weight ratings. An older E450 has a GVWR of 14050# I believe. We have a newer E450 that has a 14500 GVWR. GVWR is the maximum amount of weight that a given chassis and tires can safely carry. *In General*, the longer the Class C, the heavier. Also popular options like automatic levelers and slide outs add weight and subtract from OCCC (Occupant and Cargo Carrying Capacity), i.e., the weight of all people, pets, and stuff you can safely carry. A poster above noted that he/she wanted a 2700 pound OCCC and could only get that in a Class A. I would point out that our Class C has an OCCC of 2961#. Finally, another rate rating for you to consider. When towing, you should determine the GCWR, the Gross Combined Weight Rating of your tow vehicle. The GCWR is the totally loaded weight of the tow vehicle and the fully loaded tow weight of your toad. Our E450 GCWR is 20,000#. Hope this helps you determine what is the best fit RV for your family.
