I have a Winnebago Class C on a Sprinter 3500 chassis. I upgraded my suspension with a heavier sway bar from Hellwig, Sumo springs and Koni FSD rear shocks. I did the work myself with the help if a friend and had no issues. I would say the heavy duty Sumos made the biggest difference in stabilizing the ride. Taken all together, I'm very pleased with the difference. Sevral folks on the Winnie forum recommend air bags, but I didn't go that route.
As for supply issues, I can't really comment as i did my conversion a few years back, but I know this is a real issue today, particularly with electronic equipment. I'd recommend using reputable sources, even if the prices are a bit higher, and get your orders in.