Simon Rafferty has a piece Prototyping a tool for co-designing policy interventions, 

The piece explores how to prototype new policies. He looked at system mapping, but found it wasn’t strong at figuring out the why about intervening, or what could be done. He drafted this canvas to start a new prototyping tool vision:

Because of this limitation of the existing tools, I want to develop some form of a tool that allow for the inclusion of these insights.My first prototype of this is a simple Canvas tool that builds on a key outputs from my PhD. It starts with a relatively simple structure that looks at the PRE – DURING – POST consideration of a policy intervention. “Pre” deals with the situation analysis, “During” deals with some aspects of the delivery of interventions and “Post” deals with the post intervention evaluation. This can accommodate longer term interventions where the evaluation is cyclical and formative.