Great choice! And congrats!
If you hadn't upgraded the truck before you got the trailer, and waited until after you towed with the old truck, you would know without a doubt that you made the right move to upgrade. As it is, you'll have to take the word of those of us who have towed on (or over) the margin before an upgrade; you did the right thing!
2014 Jay Flight 28 BHBE
2015 RAM 2500 6.4L HEMI, Tradesman 4x4, 3.73
Blue Ox SwayPro (BXW 1503)
Upgraded from an REI internal frame backpack and a Eureka 1/2 dome tent!