I don’t have anyone specific in mind (and you may have already thought of this), but my guess is that one could purchase a few hours of consulting time from a faculty member at a top nonprofit management program (e.g., IU Bloomington) and walk away with a pretty good list of who the top people are in the specific domains you are looking for and/or who might be well suited for this kind of consulting work in general. Depending on the referrals you otherwise receive, asking an academic in nonprofit management might be worthwhile to maximize the use of the panel members’ time.
I don’t have anyone specific in mind (and you may have already thought of this), but my guess is that one could purchase a few hours of consulting time from a faculty member at a top nonprofit management program (e.g., IU Bloomington) and walk away with a pretty good list of who the top people are in the specific domains you are looking for and/or who might be well suited for this kind of consulting work in general. Depending on the referrals you otherwise receive, asking an academic in nonprofit management might be worthwhile to maximize the use of the panel members’ time.