New tow vehicle...6.4 hemi or Diesel?

We tow in OD everywhere and it’s “sweet spot” with the 3.54 gear is 70mph.... which is dicey with California and their 55mph policy. There’s a couple grades I’ll back off and take it out of OD. We’ve been looking at some bigger trailers and I feel our current load is probably close to max for the ole 01. Funny thing I brought an 11 home from work a few years back. I figured the 6 speed and 3.7 gear would pull circles around my 01.... boy did I miscalculate that! Our 01 has had mild mods (edge ez, rv275 injectors, I built the trans with Goerend parts) since 34k miles. I have 194k on it now. I’ll also add that I knew if I purchased the 11 it would get deletes immediately so that may have stepped it up in the power dept. either way I was a bit disappointed. Our next race trip is a nice 1300 mile one way trek and I’m not in the least bit worried about the pickup not making it. She’s a good ole tug!
I wish mine was a 3.54 my 3.73's make the 5.9 really hum around our speed limit of 70mph but most of what I have towed is like nothing's back there.