I started out without WDH and had the same experience. Stuck to back roads doing 55 and under and was not comfortable. It didn't help I was new to towing. Once I got proper WDH on there, things were a LOT better. Made it from MI to VA and back without any issues at 65 on the turnpikes, ran through the mountains and all. I know you were having issues finding space in the 2013 model, but surely the dealer's done a few of them. If not, there must be someone else who has. I think you'll be much happier with it.
2016 Eagle 284BHBE
2015 Ram 2500 Laramie Longhorn 6.7L Cummings
Retired: 2014 X23B