Those curves are a constant obstacle. I'm not sure if there is really any aerodynamic advantage or if it just aids in assembly and is cheaper to manufacture. It takes considerable accuracy to make right angles meet precisely and then the whole roof/wall seam sealing issue and ponding concerns. By rounding off and overlapping a lot of that goes away, but then you have to put the "square peg" in the "round hole" all the time.
Ladder racks with a complimentary curve cut into the crossbar would seem to be one solution, or segment the curve into 2-3 angles the width of the panels. Like an octagon for example. Could work to your advantage as Sun tracks across the sky?
Just brainstorming, as I have to deal with same issues.
McDave