RRT with bed bars, how high to clear cab for window use?

So I'm trying to track down some information regarding a problem with roof top tents mounted to bed bars that seem to be had with some people...the full use of the front facing window if mounted too low. It seems that if the RRT is mounted too low the window support bars will come in contact with the cab of the truck; thus the tent has to be spaced higher to use this window. I'm wondering for use of the Tepui Kukeman tent how high I need to be spaced off the bed in order to still be able to use that window and its associated window support bars. Who has dealt with this before and how was it solved?