This has been discussed several times on this forum and I would add it could be a personal choice. If you think it helps you, then use one. I would say an overwhelming percentage of our owners who have commented on it have elected to not use one.
Jim & Mary 2013 36 RL with Titan Disc Brakes Residential Fridge Goodyear 17.5 H rated tires MORryde IS, MORryde pin box 2015 Ford F350 King Ranch DRW
Unless you let the air out of the bag on the TrailAir, a KingPin Support won't do much.
Michelle & Ann
2018 Chevy 3500HD Crew Cab High Country DRW, D/A, 2016 RW39MB, Dual ACs, Auto Level, Auto Sat Dish, Stack W/D, King Sleep #, 17.5" Sailuns w/Disc, MORryde IS & Pin, Comfort Ride Hitch, 5.5 Onan, Res Fridge & Induction Cook Top