Help with aerial perspective

trying to finish this piece, and i want there to be mountains behind him. I’m struggling with the gradient or the background, which i guess would be the aerial perspective ? how can i differentiate the different layers? i’ve tried a few iterations of colour gradients in the background based on the reference picture: (attached) but i can’t seem to crack it - it’s either too light and looks like a big block of colour, or too dark and i feel like my character is obscured.

any other advice also appreciated!

(ps pls forgive his hands! i have to redo them)