I couldn't help myself.
Anyway, in this GIF I went ahead and went the route of animating backwards and then exporting as a PNG sequence which I then imported as a Sequence. What I discovered is that if you select a bunch of keyframes and hold down ALT and then scale those keyframe back, you can actually completely reverse a keyframe order. It's freakin' fantastic!
So, I got this crazy idea for a workflow and it goes like this:
Start off by just animating whatever you want to animate normally. When you finish your animation, make sure everything is keyed the way you want and that frame 1 of each animated layer is keyed. Now determine the frame that the animation ends on and key this frame on every animated channel (For me, it was frame 43).
NOW, select all of your keyframes from frame 1 to the last frame in your animation, HOLD ALT and click drag to scale the frames back all the way to the point that you flip the frame order. When you finish, give the keyframes a color to indicate that you flipped them already, this helps organize.
When you finish, just export the Image as a PNG sequence and then open a new file. In the new file, go to the Scripts > Menu > Image > Import Image Sequence. Now, just select all of the frames in your image sequence and hold alt while you scale them back and reverse the layer order. When finished, you should get what I show in my example.
FYI, I went into detail because someone might find this thread in the future and want to know how to pull this off.
