+1 for Can-Back if you're satisfied with an RTT as your sleeping solution. The Can-Back is a really high-quality product although the company's business efficiency doesn't always inspire confidence. I had great service before and after the sale but others have not. Anyways, my Can-Back fared all weather conditions (dust, snow & rain) really well and was more than adequate with four cross bars to support a Technitop RTT, my wife, daughter and our dog. I had plans to add a roof rack to the two forward crossbars before we decided a truck camper was a better fit for us.
Here's a link to some photos of my set-up.
Alright, this is just fancy car camping, people. Move along, move along.