I just wanted to give you an idea for the quilting. Nancy Zieman has a video working on detailed outdoor scenes, with Donna Fenski. When they were finished with the pictures, they lay tulle over the top, in a complementary color, and stitched though to to catch all the little pieces and keep them flat. Might make yours easier to quilt. I will go see if I can give you a link.
I could not find Nancy’s video, but here is one from “Man Quilts” to show you what I mean.
https://youtu.be/-3DduV4lNik