Acidity makes finding suitable plants a bit harder... Sorry I didn't see this post sooner, not a sub forum I check as much. I would plant a mix of annual rye grass a cover crop and to help hold things together. In with the rye grass I'd plant crown vetch. It grows just about anywhere... It's commonly used for steep road side banks. You may have seen it before, it's got bright white and pink flowers in the summer. Should be easy to find from most seed companies. It grows very thick with excellent drought resistance and good erosion control. I'd plant 40 pounds of annual rye and 8 pounds of crown vetch per acre.