Ultimately, I have put a feature hold on. While very minor (such as checkboxes) features may be added, I am not trying to start something as convoluted as this request.
While I understand the need for such a setup, I think it would be much better suited for a new FOG version.
1.3 is planned to be the last PHP version of FOG and while bug fixes and minor features may be backported, I think we should focus newer (and/or more complicated) features should be used to better the next version of fog.