@Sir Ver: Have you checked that your chest displays properly in-game? Are you sure the priority is set properly on your fence? I'm not ruling out that I handled priorities wrongly but I need to be sure there's a problem before spending hours pulling out my old project files and digging through priority handling scripts.
Also, no chance for screen tone. RGSS just isn't built to do that kind of advanced filtering directly on the bitmap; the best I could do is the built-in alpha-channel blend mode, rather than the comparatively simple multiply blend mode, and grayscale is a completely different beast. If you're just trying to produce a mockup screenshot, you can always import the image into Photoshop and create a new layer, set to Multiply blend mode, and fill it in a solid color with the RGB value in your screen tone. To get the grayscale in Photoshop, use Hue/Saturation on the primary layer and reduce saturation to match the "gray" value of the screen tone.