[mike49024]

I pull a 27ft, 7320 GVW travel trailer with my 2014 1500 5.3 4wd crew cab and I get 9-11 mpg depending on the roads I'm on. But I don't pull over 65mph. My Envoy with the 5.3 got the same pulling a 19ft TT.
It is what it is. Travel trailers really cut gas mileage. But we love to travel and see the US so it's figured into the cost of the trip.

Have you looked at a tune? That will provide you better throttle response, and more likely to increase mpg than any CAI could ever dream of.

My 2012 5.3 3.42 gear got 12.5mpg pulling a 7k lbs enclosed car hauler at 65mph for 800 miles. I’m basically stock with a tune. Not an apples to apples comparison, but I would think your direct inject engine could possibly do a bit better.