I just made a muslin for Vogue 2907. I must have made 5 versions of these pants, but Jennifer Stern Haseman is doing a pants Sew Along at Sawyer Brook, so who am I to deny free advice!? I'm always up for improving. Here she is:
I think a small crotch curve scoop is in order to take care of those folds. The back looks fine to me, but are the wrinkles under my booty due to some type of twisting? I'm quite certain I cut on grain. Plus, some of my other versions of these pants do that too.
Speaking of other versions of these pants, here are few of mine: