You could create an extension which checked certificates of visited sites, which includes information like country of origin, CA, etc. then have an interface for warning about certain parameters and configuring what to trust, warning about anything that doesn't meet your criteria.

The other part would be creating a way/file-format for experts to provide information about which CAs they trust and which are suspicious, then let the extension consume those.

It's not as good as built-in browser support, but it's a heck of a lot faster and more do-able.