Yes, you can use the TI web tool called webench to design easily your power convertion : http://www.ti.com/lsds/ti/analog/webench/power.page
Actually we design a new board called Hipi. It’s main purpose is to manage RaspberryPi on poppy humanoid. I start to draw it and I put an “addon” connector to manage this kind of things.
For now I create this connector to manage a clean start/stop button and possibly a batterie dedicated to head…
You have a really interresting case and I could take it to adapt my connection to your project!
If you just need to manage an extra UART, I probably can add it easily!