Just for a baseline . Get a digital angle finder . Put it on the rocker or frame , then check the bottom of the ladder bar
Did that a little while ago. IIRC it was 4 degrees up.
If the chassis is level , and the bar is up 4* the is very good and that thing should have plenty of separation . For comparison, my car is 1.9* up with a level rocker . And it works pretty good on a 275