I'm glad you're doing this. I'm all set for splitter and rear diffuser, as I've gone the 1-off route... wasn't patient enough to wait for someone to create a true functional set... here's some design inspiration for the rear diffuser
FYI - early testing on this diffuser seems to indicate that I'm not picking up much if any downforce. Will do some data-logging on it soon... But without supporting aero, it's not producing much benefit. Just something to think about...
I have a functional front splitter as well that is held up by a custom sub-frame and 4 quick release latches + 2 struts. That works pretty well for me and the struts are probably redundant even with the ~5in lip at track speeds.