As the coach doesn’t need to be perfectly level, achieving perfection is a matter of comfort.
As mentioned, the use of blocks can make a big difference. Personally, I can easily gain anywhere from 2-6” of height on one side with the use of our array of blocks. At my Parent’s home in Ca., leveling was extremely difficult and I used a lot of tricks to get close.
Blocks were essential in that case.
I feel that if I can get the coach within 3-4” of level, the jacks can gain the rest.
I’ve never measured things, and leave a fair amount of jack extension unused, because I prefer not to loft any tires.
With the air leveling on a Cornerstone, I would expect at least 3-4” laterally, if not more. Jack usage should help a little beyond that point.
2017 Entegra Aspire 44R (bunks) towing 2019 F-350 LB (Sold)
2012 Tiffin Phaeton 40QKH (Our Phaeton was so nice, we bought it twice)
2016 Open Range RF376FBH (Sold)