Multiple transparencies on one object.

I know this is an issue that hasn't been solved for at least 8 years. Nevertheless, probably someone knows a way to circumvent the problem or has an idea to emulate the desired effect.

I want to add different transparent areas to one object (black rectangle), so that the objects below (layers with maps, bitmaps and drawings) are visible in various areas, much like several spotlights penetrating darkness. The "spotlights" must be able to overlap and the position of the spots have to be easy to move around, as I want it to use in some sort of presentation. I tried a workaround using the transparency tool and the interactive Fill tool simultanously, thus creating two radial "spotlights" on the same object, but I should at least have five such areas. The mentioned workaround with the transparency and interactive fill tool show, that it shouldn't be technically difiicult to implement a tool that can handle several transparencies on one object.

I tried to use the mesh fill tool as well, but the handling of circular shapes (moving them around and scaling them) is very bad.