Area lamps, as you may already know are not supported in BGE/UPBGE 0.2x, however we can still bake lighting such as area lamp lighting onto an image.
Cycles bake tutorial. The same can be done with Blender Render, just with different, compatible materials to that particular render engine.
Subtracting multiple objects from another object with just a single "boolean" modifier is possible in Blender 2.91:
Create a new collection: Right-click inside the object list in the upper right - "New collection"
Move all the objects that you want to subtract into this collection
Create a new boolean modifier for the original object