6.7 Cummins with 68RFE - what gear you tow in?

I ordered my truck a week ago which means I have too much time to think about things. With my 2006 5.9 and 48RE, I would just put it in tow/haul mode and it would cruise down the interstate in overdrive most of the time. With my 2015 6.7 and 68RFE, should I just do the same using tow/haul or also limit it to the first OD (5th), or what?

My fifth wheel is about 10K lbs. and 2006 had 3.73's and 2015 has 3.42's.