Being a boondocking area there are no time restrictions for arrival. From a safety standpoint, I wouldn't want to arrive after dark, at least in the area we camped. There are no lights here so navigating the many vehicle trails to campsites would be very tricky. There are some sites just off the "main" road that you could safely pull into, if they aren't already occupied.

It would be a lot easier to find a site before it got dark.

Yes, but sometimes it is hard to locate a good spot at night if you're not familar with the area. You can check in the next morning. No problems. It's serve yourself...