Back to digging in at camp sites...
I would not normally do this, because it may be destructive to the pad area. Digging a hole in packed gravel and then later tossing the material back in is not the same as leaving it tightly packed.
On the other hand, if the campground operator says it is okay, this is a great way to get level without getting excessively high. We had our motorhome in an RV park for a whole season, and the operator suggested doing this. The site sloped significantly down from rear wheels to front (which is a long way with this motorhome), and it allowed us to level without an excessive step up, or raising the front wheels off the ground with the leveling jacks.