A friend of mine got a map form the Mount Adams Ranger Station that is one of the best maps I have seen of that area. I dont know if it had gates or not but state and federal lad was marked on it.
Other than that you can get a DeLorme Atlas & Gazetteer or a Washington Road & Recreation Atlas by Benchmark. The Benchmark has a few gate marked on the maps but not all of them. If you buy one of these go to the bookstore to get it. If you buy it on line you might not get the most current one.