"In my research F-250 has sway control."
Well, if you researched more, you would find out it's only for the most extreme instance of "sway".. Not just for your everyday, running down the road "sway control"... ;)
My F150 has that and it's the last thing I want to see engage on my truck.. Why? Because if it engages, you are in a lot of trouble and on the verge of crashing..
Anyway, I would question the advice of your friend as it's nothing I would follow... Towing 18,000 lbs or not with a 3/4 ton truck...
Good luck!
Mitch