Well.. I'm not sure how much a sway bar will help.
Sway is side to side rocking, You know like folks singing "We are the world" Of course what chassis you have may affect this, Workhorse put good sway control on my Intruder,, Ford, I suspect, based on non-truck, experience may need help.
A larger problem with motor homes however is what I call "Wagging" that the body moves sideways on the springs, not rocking side to side but sliding so the tail moves a bit right or left and the nose moves left or right.
A TRAC BAR controls this (Also called a pan-hard bar)
it locks the house squarly over the axle previnging this 'Wagging" like motion.
Made a big difference on my 2005 Intruder
Nothing adds excitement like something that is none of your business.
2005 Damon Intruder 377W Radio Active as WA8YXM