Like bigfootford, I too can tilt my panels. Also like bigfootford, I do not need to, and I only have two 65-watt panels. Initially, I was going to buy my panel mounts. The store discouraged me against tilting mounts. They said it is very common for people to forget their panels are up, and drive off. The damage can get very spendy.
I made my mounts tiltable, but have only tilted for show and tell. My panels are on each side of the escape hatch, and standing on the bed, I go through the hatch to tilt them. It is not enough gain to be worth the effort.
As you can see by the cabover roof line, my panels are not flat. actually on each of the panels, the front outside corners are about an inch lower than the opposite corner.