I used a nylon bristle brush and a very dilute mix of laundry detergent with warm water to clean the one I had. Rinse well.
It never got really dirty or stained, just dusty then wet.
I didn't treat the vinyl tops of the bunkends. I used 303 HiTech Fabric Guard inside and out on the canvas.
FOR SALE 2014 BOSS 6.2L F350
2012 Surveyor SV264