I really don't understand the logic in partially leveling the trailer before running the auto level. The only issue I've ever seen is when the jacks can't reach the ground enough and you get the out of stroke error. I always put blocks under the low edge of the trailer (depending on the direction of slope) and never have any issues. I would put blocks under all 4 jack, but I don't have enough
When the Lippert says start with a level site, they just mean you should not have a slope which causes the jack to run out of reach before the trailer is level. It does not mean you need to first level the trailer. Note that if you pull the trailer tires onto boards/blocks, you're only moving the jacks on that side further from the ground.
Out of stroke just means add more blocks under the low edge jacks