Hemi and towing unfortunately does not equal fuel economy Hell even my 11 with my 4000 lb holiday trailer will only pull 11 to 12 mpg, best I've had was 14 mpg but I was averaging 55 to 60 mph only. Your best and cheapest mods for mpg would be CAI or even a K&N drop in air filter, exhaust will help a little as well. I run synthetic oil as well, it can get you a mpg at the very least. Turning off the mds is only required if you notice the truck hunting for a gear. If she is constantly downshifting on you put her into tow/haul mode. Back in my mechanic days we always said that the best fuel mods were to lubricate and help the engine breathe, so intake exhaust and keep the engine well maintained.
Look forward to seeing you around the forum, drop me a message if there is anything I can help with.
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