Can you put the money for the day pass in the after hours drop box?

I can't really say because I always make it my buzz to come during the open hours. An that way u can get a spot u want ..sorry

Thank you guys! The gate was open but I knew there was a fee so I wasn't sure where to put it because it was at 7am and the office opened at 8:30

Yes

It's a common feature across all the Texas state parks. So yes.

I did, they had envelopes with a window sticker, as you fill out your info, it becomes your window sticker, the envelope you put your fees in, there is a drop box for the envelope. Fees are listed by the dropbox, on the left of the parking spot across from the camp office/store.

Of course you can