Creating Illumination Glow From Light Sources

Some background: I design realistic fantasy and sci-fi maps for tabletop RPGs, and have used a variety of techniques to "fake" illumination around things like candles and torches. However, nothing really satisfies and looks realistic. One technique just involves using a white-filled circle with transparency and a vignette effect to imitate the pool of light that would be present around light sources. 

In the first image, you can see the table I want to illuminate, along with the floor. The problem is that it requires a lot of layer chicanery to try to hide things, and I would rather just have a wqay to make the illumination source as above, apply a Multiply effect (maybe? I think that's the one I would use?) to make it look like it's illuminating whatever is under it, and then use drop shadows to fill it in. But...how do you layer it with a drop shadow? You can't. Walls>illumination>table/chairs>floor. If you drop a Drop Shadow in between the table/chairs and the floor, it looks like the drop shadow is being faded out by the fake illumination. 

https://imgur.com/a/wn8jS1n

So in the second image, you see the table and chairs, and the wall where I would like to cut off the overlaid transparency. If I just draw a square and try to overlap it and use the Join functions, it just shrinks the vignette rather than create a hard solid edge to the vignette-transparency. How do you force CorelDraw to be able to cut off one side of the transparency without making it just shrink? The first image is what I would like to achieve (using a filled box here just for illustration purposes) using the joining functions. 

Is there a better way to create more realistic illumination? Any help would be greatly appreciated! Thank you!