While is a very neat ideia to have this background as layer 3, I'm gonna to reject this because of some issues.
First of all, why the sample level includes graphics file that aren't going to be used? Make sure to include only the layer 3 stuff. Anything that isn't used by the rip shouldn't be included in the sample level.
The second issue is organization. I got confused because you named the two backgrounds like BG1 and BG2. For easier understanding, it would be better : "Pyramid" and "Pyramid (Alternate)". Please be more careful, it should be easy to the users to understand how to insert the graphics.
The third one is that one of the pyramid background is missing some tiles. Please make sure to include all the necessary files. From what it looks like, it's missing one file.
And lastly, not a rejection reason, but this submission in particular, has one bad screenshot. I recommend you to take a print of the layer 3 window, instead of cropping it.
With that said, once you fix these issues, I'll shall accept this layer 3 rip.