Damn, so many concerns about messing up the car. It's just a car! Use it!
I put in the Rhino Rack ditch mount setup and I love it. I have the square steel bars, and I use it for everything. The car is low, so it's easier to load than a full size wagon or SUV. It's amazing and really makes this car easy to live with.
It can return to the stock look if you buy new gutter strips.