OK, before anyone's tempted to get into a big debate about the usefulness of being able to rotate and tilt the panel let me say; I'm doing this because I enjoy tweaking the last milli volt out of the panel, not because it's something I think you have to do.
I've done this for years on boats and it's just second nature for me to twist and tilt without even having to think about it. I don't consider it a big effort to tweak it during the day. If I'm away it'll just get left in the default South facing tilt.
The plan is to mount this one on a collapseable pole on the front side of my tongue box. In the fully raised position it will clear the roof so no matter where the sun is I'll be able to get the optimum exposure. In a totally shaded situation I can still put a short tube on the mount and use it as a portable unit.
The 2" tube may look like overkill but in the flat "down" position it'll no doubt get a fair amount of buffeting and the 2" tube has a much higher torsion constant than 1 1/2".
It's an experiment, maybe it'll work or maybe it'll end up just mounted on the roof. Time will tell.