I was thinking IF I were to try it. Take small pieces at the bottom of the leaning tree, like you would any tangled tree, to try to get it in a more vertical position. It would most likely roll out of the kickstand tree at some point and continue the path of its fall. Any undercut on that leaning tree is going to drop that base like a ton of bricks, and probably unpredictably too.
I'll toss a rope around the leaning tree and pull like hell with my truck!