Just me but I'm going to try and be as level as I can. Got this from the forum. I like the way he explained it.
With TV and 5er hooked up park on a level area. At the pin location measure from ground to top of bed rail, call this "Measurement1".
Now chock the 5er wheels and disconnect the TV from the 5er, pull TV clear of the fiver, then level the 5er. Then at the pin measure the distance from the ground to the bottom of the 5er over hang, call this "Measurement2"
Now time for math (measurement1 + 6") - measurement2 = needed lift at axles.
(from rhagfo on RV.net) Thanks