Can I keep a leaf compost next to my regular compost bin?

I think maybe you're making composting sound more difficult than it needs to be. Yes, everything rots. Throw it all in one bin, and turn it occasionally. That's all you need to do. The simplest composting is your 3' pile. Make it more durable by adding any reinforcing you want, starting from wire fencing up to a wooden or plastic container. The key thing is make your pile at least 3' square, so it heats up enough. Most of the other details are trivial. Old time gardeners used whatever was handy, even old pallets. It really doesn't matter much.