Ballasted Racking recommendations

rdg1

Hello all,
I need to install my 6 panels on a flat concrete roof.  The panels are 40" x 60".  I have been reading reviews for the Ballasted Racks which I tend to like because I would not need to drill into my roof.
The location of the house is 27 Degrees N longitude.  Based on what I have read, it appears the best tilt angle, depending on 2 seasons, would be 12 to 42 degrees.  I have not been able to locate an "off the shelf" racking system that would provide for this degree of tilt.  Most of them seem to be a 5 or 10 degree of tilt.

All that being said;
1. does anyone have experience with the ballasted racks,
2. suggestions?

Thanks for your input.