several Heartland 5ers have an LCI 6 point leveling system. -- Almost all Cyclone TH-5ers, almost all Bighorn 5ers, a lot of Sundance 5ers. Look at Heartlands website. Most Heartland 5ers can be ordered with 6 point levelers.
Consider this, If you are too far off level side to side. You will still need to drive on blocks on one side. If you are too far off level front to back, you still need to add blocks under the feet of the jacks that will extend the farthest.
You never want a wheel to go off the ground in order to level. Remember also, these jacks only have so much travel, and you always want each jack to exhort about the same amount of "force" on the ground. If one jacks "pushes" very much harder than the others, it could affect the slide room operation.