http://www.adventurerv.net/camco-acculevel-level-p-4317.html?gclid=CMvH-LCu18ECFRZqfgodSm4A7A&utm_campaign=partsfeed_ppc&utm_medium=cpc&utm_source=Froogle
If you can get all that in. It shows a level made for the pin box and mounting brackets. Easily visible from the driver seat. Each small division is 1" and the large are 2". That's how much you have to raise the side the ball is on. makes leveling side-side very easy. Front to back is with the landing gear after unhooking.
I wouldn't be without one.
As said level the rig first then install the pinbox level and adjust it for a level indication.