This sounds cool and I’ve never had an opportunity to do this myself, but if I did, I’d opt for Way 1. Then once I was happy with the animation, I’d create a comp for Side A’s dimensions, and add my animation comp to this and move it so that the far left of the animation is lined up with the left of the Side A comp.
Once I was happy, I’d repeat the process for Side B, but the time position the nested comp -4032 pixels to the left. And repeat this for the final two comps.
This method gives me flexibility, as if I need to amend my animation, I only have to change the original (and re-render) and I’m not having to copy key frames etc…
http://www.YouTube.com/ShiveringCactus – Free FX for amateur films
https://shiveringcactus.wordpress.com/ – FX blog