I've been holding off on the back lever until I achieve the front lever, and I don't really have much time or ability to add in anything more right now. I will try adding in some German hangs and maybe some skin the cats to my warmup. I have limited space, so I may only be able to do the skin the cats in the tuck version.
I've been neglecting to stretch the shoulders in the manner of flexibility that's required for the German hangs. Maybe that's part of the problem. There always seems to be more bases to cover...