There really are no safe jack points for a Hi-Lift, you use what you have to use on the trail and pray the Hi-Lift doesn't fall over on you or slip out and let the Jeep crash down. A Hi-Lift is an unstable jack that should only be thought of as a jack/tool of last resort when nothing else works.
Hopefully this new Hi-Lift isn't really your only jack. The OE bottle jack is what you should be using for tire changing duties (don't use the Hi-Lift!) and it works well up to 35" tires. The factory jack is even suitable for changing 37" tires in a pinch without much extra height left over.
Most of the time, inserting the Hi-Lift under the rock rails is the safest way to use it when it has to be used.