If you pay the $10 camping fee at Murrell Park you can stay over night. But just tell them your camping, don't say you're just fishing. We told them we would pay the camping fee but were just gonna fish and they went nuts. I just couldn't understand their logic behind having a problem with that. They got their money so what's the big deal? We eventually talked them into but it was a waste of 10 minutes.
But honestly, I would avoid the parks if you wanna fish late. Just look up the trail heads for all of the hiking/biking trails. Those trail heads are open 24-7 to my knowledge and are free.