Having had about everything on various roof to transport, I suggest you get a board up there and make a few test drives.
Apart from not seeing overhang trafficlights - and that could lead esp. abraod to interesting talks with people in uniforms - you could find having that serious sun visor creates unpleasant forces.
If you want to sleep upstairs, you could consider a hard shell type solution
You could make a very nice one in the size of the 90 roof. The one in the picture is our old Hard Shell that has been everywhere and uses 3 FF roof bars on a 90 for a good fit. On the 110 it sits in the Bronwchurch. Making you own is not to difficult.
Bon Courage !