Thank you, perfectly explained 
Yes, been doing research on it for few months, read many discussions on designs, and CG considerations. I've designed a quite low profile roof rack. Keeping it close to roof as much as possible, walls are not too high, and mounting points are to be tested with load.
The factory installed roof rails look quite sturdy, but I am also looking to see if they can be easily removed, and I can make direct metal mounts which will fit at rails' spots.
Will be sharing more details soon.
