I think looking for ways to encourage more new managers and provide a training and proving ground for those who want to be managers is a good thing. I just don't think this approach will work for that.
Maybe you can be named "Review managers manager" :P Out of joke, this position can really help to change the actual frozen review queue. Tomas has made several posts in the past with the title: "Review managers needed"... But hi is very busy with other boost stuff, this burden can be taken by other person. You have done three reviews, that is a lot of experience. You know what it is needed. IMO a person in this position can encourage active boost users to be review managers. For example, if another container library is presented into boost... he can gently ask some of the containers libs boost authors if he would be interested in managing the review. Best Regards Matias