I remember Walthers carried that Miller working drive-in. IIR, it was a bit pricey. MR qand RMC have had suggestions on using small screen pocket TVs connected to VCRs and DVD players. I also seem to recall a suggestion that showed a couple carefully arranged mirrors to reflect a somewhat larger portable TV from under the layout onto a screen on the layout surface.
Drive-ins aren't dead. In fact, there is a two-screen drive-in in North Ridgeville, Ohio that still opens in the summers.
I remember going to that drive in all the time as a teenager, with a continuous stream of Conrail trains passing by, At the time I thought they were annoying. Now I'd face the truck to the tracks.
I recall seeing a commercial (Verizon IIRC) with a phone that had a projecter on it. They showed the guy projecting some movie trailer on the wall and I thought-why would anyone need something like this? Guess I know now, use it for an HO drive in movie projecter. The phone should easily fit into a concession stand building and the screen could be exactly that, just a screen with nothing to hide