I GM D&D 5e for a group of players I know IRL, and I'm wondering how you guys handle a situation I keep running into.

The situation is, for many 5e modules you can buy the maps online, which include images of a GM map and a player map. So far what I've been doing is putting the player map on the background layer and the GM map on the GM layer for me to use as notes. But the problem I keep running into is that, since the GM layer is transparent and above the token layer, it makes all the tokens difficult to see.

Does anybody know of a better way to hide a large image from the players in Roll20? Ideally, I should be able to see it clearly, they shouldn't, and I should be able to see the tokens as clearly as they can.