After reaching the first main flat spot on Backdoor, look for a small gate on your left.
Go through this gate and continue to stay left.
This low angle run follows this side of the resort's boundary line, with fun trees and a decently wide run.
It will slowly cut back right toward the resort.
Make sure not to miss the final traverse back.
There will be a small sign telling you to cut right.
Towards the end of this run there are some fun cliffs that you can hit when the snowpack is good. Halfway down this run there is an access gate on your left that leads to the Solbright trail, which leads to Solitude Resort.