If outside the pad is less rocky, that could be better. Depends on how big your tent is. You might be hard pressed to find a bare area outside the fence for a larger tent. I saw people pitching in the parking area.
The area inside the fence is pretty hard and rocky, so if you can find a soft spot on the other side of the fence, I would. I saw people with tents on the other side of the fence. It may or may not be allowed, but I didn't see any warnings about it.
When we were there everyone was parked within the fence area on the gravel. I assumed outside that fenced area was private property. We did see cattle roaming right outside the fence, not sure what their Interest in a tent would be 😊
When we were there year before last, we saw folks try both places. Wind picked up near dusk, so they weighted down the side with some large rocks that are plentiful around the pad. Sadly both were down by morning.
Both were larger tents, perhaps a smaller domed tent would have withstood the wind better. Oh, bring steel stakes, or those really large/long nails. The ground is really rocky.