I've been to a couple MD state parks and they both told me drones are not allowed. Of course there is the Airspace loophole of taking off from outside the parks borders, but that's risky, limiting, and can still be frowned upon by park staff and potentially rude to park visitors if you're flying low. So unless somebody can provide evidence that you are in fact allowed to fly in MD state parks, I would replace Sandy Point with something else.
I would also note that the other locations might have restrictions set in place by the properties. It's not just the state and federal laws you have to follow. Every park might have their own restrictions you need to look into so you can't assume that it's OK to fly there if it's not a National or State park. For example, Fredrick County has over a dozen parks, but only 5 allow drones WITH prior approval.