I am also interested self-directed learning and credit – not so much as credit for prior learning but as facilitated progress. Looking at your rubric, it could be really helpful, or it could become the “end” rather than the “means.”
Taken to its literal extreme, it would be simpler just to take the course, than to have to satisfy all these criteria – doing the research to know what you would have learned if you took the course, and than proving that you knew that.
I’m trying to define a more collaborative model that is a process. The assessor / facilitator knows what is required to be learned to meet the credit criteria, and works with the learner. The learner does most of the directing, but the facilitator ensures that the core requirements will be met and the learner doesn’t get stuck down some rat hole for lack of learning that is the scaffolding for the learner’s line of inquiry. This gives the learner flexibility for directing their own learning but ensures that they will be credit worthy in the end. Something like a PhD program model for 4th graders.