what should and shouldnt be ok for a v6 to tow?

Having towed a 3500 lb TT with a 4.0L V6 and manual tranny with my 99 Ranger, I was fine unless I had to start on a hill, then I was afraid my clutch would glaze before I got moving. I now pull a 9500 lb five with a 3.5 V6 (Ecoboost) that is rated to tow 11K and it is so much better. There is decent engine braking in Tow/Haul mode that relieves brake wear. I've been through the mountains of NH and WY with no problem going up or down.