Is there a time cut off when you can arrive late perhaps a bit after 10 p.m.?

You can check in anytime during the night using the self check in. Just remember to check the bulletin board for your assigned site if you have reservations. It will also tell you what's available if you don't have reservations.

We rolled in late. Found a spot. There's a pay box with envelopes. Didn't have exact change., Bring cash and singles. Checked in the next morning anyway. No problem