Can you stay at Robert Moses past 7 P.M. on the 4th of July and can you see the fireworks from there?

You can stay until dusk only

I believe the park is open until dusk. Not sure about the fireworks.

I used to ONLY go after 6 pm so I don't have to pay for parking. No lifeguard on duty though. Who is going to kick your out . Suffolk PD ? Park police? Not sure about the fireworks.

No, obviously, since it is just another "regular" NY state run fascist over regulated beach/park