I have found Yelp.com to be the best place to get reviews on any service organization including repair shops. It surprised me after a bad experience with a local shop to find 5 bad reviews on Yelp. Prior to that experience I had only use Yelp to find restaurants while traveling.
I think it is safe to generalize and say that independent repair shops as a rule do better work than national chains and tend to be more honest in dealing with their customers.
Not all RV repairs require a "RV repair shop" with the loose U-bolts a case in point. Most garages can do this type of repair and for suspension fixes in particular I trust shops that do this type of work specifically to earn a living over a general purpose RV shop.