Implementing a ProjectSdkSetupValidator which isn't DumbAware.

In order to determine if an sdk is setup correctly it is convenient to use "smart" features to check for required symbol definitions etc. Unfortunately the built in ProjectSdkSetupValidator is called from a DumbAware class. How would I go about implementing my own ProjectSdkSetupValidator interface which is only called once indexing is complete? I'm particularly uncertain about how to create and add the relevant notification panel.