How deep is your room? I also have a small basement theater but my house is on a slight slope and only the front half is basement. The back half is crawl space.
I built cabinets for my components and projector myself that extend into the crawl space. The projector opening is small but the cabinet interior space itself is very large, plus I have thermostat-controlled fans and vents. This gives me a throw of
17.4" inches on to a 115” x 49” inch screen. I don’t have to worry about weight.
I don't have rear space to do an in-wall box. Has to be ceiling mounted.