Your leveling to high and flexing the chassis frame should only level to stabilize the coach.
If your flexing the frame of coach or using AUTO level you should level each side rail manually.
Flexing chassis frame may result in a popped windshield.
may explain more for you covers all slide systems and leveling and follow all links for information.
This is the link
for leveling manually to stay out of trouble.
"Ken" not sure I told you all the links below in my signature have more info for your Newmar.