Your chassis has two weight ratings. Gross Vehicle and Gross Combined. GVWR is max loaded weight for the coach itself, 14,500 for late model E450. GCWR is Coach (not to exceed GVWR) and Trailer (or Toad) and that's 22,000. BUT it's limited by Coach and Hitch. Common tow rating these days is 5,000. Older coaches 3,500 and some of the newer ones 7,500. From experience:
The lighter the better for the vehicle you tow along for your camping outings. It will tow 5,000 but you'll feel it in performance. Target for 3,500 or less. You'll need a supplemental braking package.