Your long trailer is a big sail and any mild or more wind can and will push it around. A good sway control for sure is desirable. Our long gone 27' TT would push our then 2WD F150 around until I added the sway control. Then there is your tow vehicle itself - do you have the WD bars 'cranked' up to the point that it takes too much weight off of the TVs rear wheels and puts too much of the load on the trailer and TVs front wheels? We did that way back in the '80s. Once! Do you have sway bars on the truck's suspension?
Dave W along with my DW, Susan and our poodlepups, Callie & Molly,2011 Ford F250 6.7 CCLB, 5er Hitch Option w/B&W Hitch,,Ride Rite air bags, 2014 Montana High Country 343RL (38')