We towed our 195RB for 5 years with a RAM 1500 with the 5.7L v8 and the 3.21 gears. One trip we did frequently was from Seattle to Kanab, UT. There was a good mix of mountain passes and flats and overall the 5.7L would turn in an average of around 10.5-11 for that trip. With a good tail wind on the flat we could see upwards of 14+ - a stiff headwind could take it down in the low 8's. Unloaded around town I would see ~13.5-14 and empty highway I hit 19.7 one time. In my opinion the better towing experience would be worth the potential trade-off of slightly less mpg.
TT: 2019 ORV Timber Ridge 23DBS, Blue Ox SwayPro 15K/1500
TV: 2019 Ford F-250 XLT SuperCab LB, 6.2L, 4.30/e-locker, 4x4, 164" WB, 3216 payload
TV: 2014 RAM 1500 Big Horn CC (Traded in)
TT: 2015 Jay Flight SLX 195RB Baja Edition, Andersen No-Sway (Traded in)