You may also just want to add a lot of thread painting to the mountain with the snowy look...I'd put some dark green/blueish below what looks to be the snow...and a grey to silver on the snow. Make the sky stand out by tracing the mountain tops several times... That and adding the fence in, should be perfect.
I need to try something like this. I'm taking an online class also, on the Quilt Show... my resulting tree is not very good, lol.
Marge