Just let the engine handle it by making the objects movable and using dynamic lighting.
Aside form that, if you had to leverage the engine for whatever reason.
single empty level with just light and object posed as needed…
Bake.
Access lightmaps and export the generated file.
Repeat with different pose.
Now you have the 2 textures to use. You can lerp between them in the material as the object is opened/closed which will give you a somewhat wierd effect - however it can work. Depends on what the object is really.
Also, AO has nothing to do with the enviroment (lack or presence of a roof).
An AO map is just how an object is “most likely” to be lit.
Basically it’s a way to make corners/crevices darker than they would otherwise be without using the AO map.
re-read up.