This rack is rated for 500 lbs, but I also have a third cross bar if I wanted to add it. The dolly is a Seitech dolly but any dolly would work. The dolly sits in hooks, visible in the photos--they're the hooks sold for hanging your bicycle in the garage. I hate driving 55 with my trailer here in California; I can tell you that the boat feels very solid at freeway speeds with no appreciable wind noise either. I haven't checked my MPG yet, though