Public land in Maryland takes a couple different forms. You mentioned Liberty and Prettyboy Watersheds. They're bow only which is good. There are good numbers of deer running around in there. A great deal of both properties border farms which feed the critters. TOns of acorns etc everywhere. Yes there are pockets that really get crowded, but there are opporotunities to find hidden little corners off the beaten path where every deer heads when the pressure gets to be too much. There are other such properties scattered throughout Maryland. Each has it's own system, season pass, day pass unreserved, day pass reserved etc. Some limit the number of hunters per day etc.
There are also other Wildlife Management areas where land has been set aside for wildlife such as Hugg Thomas on the Howard/Carroll County line. It's 365 acres, allows 6 hunters at a time. Permits obtained 8 days ahead of time via visit to the Gwynnbrook office or through the phone in system. First come first serve. There are several of these areas throughout the state run by various offices. You really have to get the Hunting manual to find all the whyfores and where nots.
You mentioned the Cooperative Wildlife Management areas where a farmer allows the DNR folks to regulate access to and from his land. I've never hunted one of these places but had a friend who did years ago. These places are usually reserved permit(ahead of time). The Coop managed properties are usually limited access. By that I mean they may only allow hunters on M, W, S or T, TH, Sat or something like that. Controls pressure but it makes it tough to get used to a spot and know what's going on unless you're lucky to get a pass all the time.
Then there are various State, County, and National Parks in Maryland that allow some form of hunting. You really have to get the book to learn all the pecular rules for each. They vary. For example, the Patapsco Park that runs from nearly the Pa line to Wash DC has opened sections for hunting, but you pay a traspass fee of $50 or something for the year, must shoot a doe or two first(don't know exactly) and you can reserve two dates ahead of time. By that I mean you can have passes for two different days at a time in your possession. When you use one you can get another.
I used to hunt Hugg Thomas a lot. I had a couple hidden away spots where I always got a buck or two. When I stopped hunting it I revealed my spot to one of the DNR people. He now gets a deer or two or three there every year. My point being, if you dig around in any of these places you'll have plenty of opportunities.
PRIVATE LAND???? You beg, cry, pound your head on the ground, .... whatever it takes. I've just become a male hooker.[8D] Anyway, the best way is through someone who knows someone who once knew someone in the know... if you know what I mean.[8D]