Ultimate Overlay Plugin will allow you to add custom images (layers) into your map. (Parallax, Ground, Fog, Light Layers)
I really like your plugin man, but it has one major problem, It does not support bigger resolutions. I´m using Yanfly's core engine plugin, with 1400 x 810 as the size of my game screen, and the layers are not showing properly. I hope you can fix that, but your plugin is great anyway.