A trick you can try is to put the camera at the distance you want it outside the room and then use the group editor to delete the blocking polygons in the wall. The problem with that is sometimes it messes up the UV map so textures go wonky. The hole in the wall may also show up if you have any reflecting surfaces, depending on the angle. Deleting polygons is not undoable so save your scene first if you try it.

Another option might be to add a new material zone with the grouping tool and make the polygons transparent. You will get the slowdown in renders that transparencies cause for your whole render. And again, the hole may show in reflections.

Either of these could also be done with an outside modeler, but I don't know if you have one you're familiar with.

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