I have read the "dont put jacks under a slide" more than a few times on these forums and many others as well so I never bought them for our rig. I do as "rbq" recommended....here is my process upon arrival at site once I disconnect tow vehicle...
I leave the slides and bunks all in tow mode (fully retracted) until I have rig level and all four stabilizer scissor jacks extended. When I do this I leave the road side (drivers side/slide and bed side) just a smidge prouder so i'm not completely razor/laser eyed level. With that setup in place I double check all the 4 corner stabilizers to make sure they are snug to the pads on the ground and when the slide extends and the beds are dropped, the left-right level bubble always ends up pretty much dead on.
No matter what you choose, the level doesn't have to be perfect just reasonably close, or at least close enough that the drink/beer glass won't spill when set on the table!
Ed & Chris
Josh & Jaclyn
2012 Suburban LTZ
2013 Rockwood Roo 233S