I have a 2-piece system from Thule - that is no longer available. The 1st piece is the Thule Space Station. It is a tilt-away unit (for pickup trucks) that is the base for Thule's bike racks, snowboard racks, ski racks, cargo trays:
The 2nd piece is a 2-tray fork-lock bike rack (there was a 4-tray option as well):
The 2 pieces combined are very heavy, and solid. Since the Space Station was designed to hold a cargo tray, it can support a lot of weight. The added benefit of the tilt-away is that it allows me to tilt the bike rack away (with bikes on it) and put a step ladder behind the coach to reach the top of the window and marker lights.