Is there a way to configure custom keyboard layouts? There are a lot of apps out on the market that you can install to have a customized Keyboard with different languages and functionality, but I didn't find a way to get my own custom Keyboard layout on my device.

Is it possible to get this running easily?

I would like to have the left half of the single handed Coffee++ Layout on my device:
One way to do this (although I can't say it will be too easy) is to create your own custom IME (input method editor).

While it may seem like a daunting task, and there is a good chance that it is, you aren't the only one who wants their own input method. So here is a pretty popular Stack OverFlow that could help you out: How to develop a soft keyboard