Which day of the week is the least crowded?

I'd say during the week.

We went on the Thursday after the 4th of July and there was no one else there

We went the weekend of memorial day and the bar was open. There was a little backup getting into the cave but went pretty smooth after that.

We went on a Saturday and did the golf cart trail. The place was pretty packed but the trail was actually really empty

We did it on a Tuesday afternoon and there was no crowd at all, except the bar at the cave...still no problem