We stayed here as an overnight stop during our summer trip.
There is not much in Hardin at all, but the campground provide plenty of space with the sites. We had 50amp for our trailer and water and sewer hookups.
I don't think the staff at the front desk were very enthusiastic about their jobs…they seemed like they weren't too happy to have to deal with another camper showing up for the night.
There were quite a few other rigs there when we stayed, but no one that looked like they were staying for long term.
It’s the most reasonable place to camp if you’re stopping for the night to see the national monument.