Other ideas that are more palatable, easier to implement and possibly covered under existing law:

SEC “Seal of Approval” – the SEC could take a position on each and every BOD nomination for every corporation.  Start with weeding out the obvious conflicts, but with experience can develop both a set of minimum standards, rule-out conditions, and possibly even scorecard metrics.  [This wouldn’t be a bad idea for a new website service developed privately].

SEC Added Nominations – rather than replacing (initially) the existing nomination process, the SEC could enact “sponsorship” of nominees into BOD votes.

Both of these may influence both BOD governance by corporations, as well as shareholder behavior.