ed4ster
After i commented on your post I spoke with a friend who pulls a 40 ft 5th wheel behind a 2013 6.7 liter Ram and he said his uses 2.5 gallons of def/1000 miles. Similar to your usage for sure. I have 2017 Melbourne on the Sprinter chassis with a 3 liter but haven't put enough miles to know what its usage will be.