I just took a couple of pics for you. In both pics, the ruler started atop the factory longitudinal black plastic roof strips.
The the first pic shows the top of the rearmost loadbar. The Leitner loadbars are lower than the perimeter so that's not your highest point but that'll be your height increase across the entire inner load "platform" of the rack.
The second pic is more meaningful for empty rack clearance. This shows the distance from factory plastic strip to the top of the Leitner perimeter frame at the rear, looking forward. This is your highest point since Grenadiers have a natural rake. I tried to align the front and rear perimeter frames in the pic so you can read the measurement squarely. I'd say that's 2 1/16", maybe 2 1/8" if you want to be safe.
One other note ... your safari windows, if you have them and they're open, rise taller than the Leitner rack. That's how low profile this rack is.
Hope this helps.
Looking forward, from plastic strip to top of rearmost loadbar:
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Looking forward, from plastic strip to top of rear perimeter frame: (highest point of empty rack)
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