I’d just say make 3 new layers, one right after ground (either make it another ground or a new mask 1) (for lower objects), one mask (for taller objects that affect the lower portion of your player, like the cliff), and one fringe (for trees and such). Not sure if this would work the best, but that’s just my simple way to do it.
Now, if you have time in the game, then you might want so really cool way to make shadows stretch across the map more, as they do because of the sun. Maybe make an attribute for it and an editor that you can insert a new “shadow” image (so a image of the shadow, like a tree’s shadow) that you save then put at the base of the image on the map. I think DX8 has the ability to skew an image, but I’m not 100% sure. Might be need to look into.
Hopefully these ideas spark something