I've priced a few to project onto a table since I'd prefer minis be on the map, but the rigging I've seen is a little awkward. "Player version" map handouts would kinda do the same thing as you're suggesting, if I'm understanding you correctly. It would give away the structure of the level but not what might be found there. At this point, there are probably Undermountain maps for sale at Aurora's Emporium given how frequented by adventurers they are and at least drawing vinyl map versions of specific areas if and when combat happens would only require copying what's in hand. That's likely the only way to do it given my circumstances.Portable projector. They make some for a hundred dollars or so and you can project onto any clear wall using the same approach as above.