I see you have a 24' 5er and a 18' Ranger.
I towed double for over 8 years with a '90 chevy 2500 350 5.7 TB engine with a whoppin' 205 hp/300 torque 4L60 tranny and 4.10 gears.
Boat was a 3400 lb 18' Asto with a GT150.
5er was a 26' 7600 GVWR Aljo.
We pulled all over OK/AR/MO/TX/KS and parts of NM/CO. That was back when the speed limit was 55 and most folks didn't run much faster.
Your 6.0 has gobs more hp/torque so IMO you shouldn't have any issues unless your trying to keep up with the flow.
My advise is keep it slow