The Norcold service manual for my fridge (N811) specs 6 degrees max front-to-rear, 3 degrees side-to-side.
You might be able to find your manual here: http://bryantrv.com/docs.html
IMHO, 5 degrees is too close to the spec, especially when it's just a guess
The way we do it at home is like Neil mentioned, we put the low wheels up on blocks (making sure the entire contact area of the tire is supported by the board or whatever you are using), the do the final leveling with the levelers. I can second the frame twisting caution, too. If we don't have the blocks just right the entry door hits the frame, which indicates our frame is twisted.