This is good in theory, but in our online world, a company's investors, supporters, vendors, customers, etc. want to see who's behind a company. And if it's a small venture, the story usually centers around the founder -- how did he/she start it, why, and so on. So, if you're going to create an alias, then that fake person needs to have a fake identity on LinkedIn (for example). But this is really hard to do. The fake LinkedIn person should have a face (profiles without a face are less trusted), as well as an extensive history. But more significant... this LinkedIn "person" needs to have connections and recommendations; otherwise, no one is going to see this "person" as credible. And it's pretty much impossible to get connections and recommendations for a fake person.
And after all this, if you could somehow pull it off, you just run the risk of being seen as shady and untrustworthy. If a blogger finds out your CEO is fake, that will just invite criticism and a social media firestorm. So, really, I just don't see how this is workable at all -- particularly since the original poster was specifically talking about expanding reach into social media and "real" media.
The best suggestion I can think of is trying to find a social-media person (intern, whatever) to do as much as possible under their identity. It won't totally shield you from being exposed, but it will reduce the likelihood. If all the publicity is coming from another identity, it's far less likely it will hit the connections of your boss and co-workers, and therefore their attention.
Alternately, you could take on a person to do this, grant him/her a glorified c-suite position for his/her efforts... perhaps the person could even be a in a minority-equity position. But the bottom line is, you have a person for all "communications" who is not you. Then, at some point in the future, if you are in a position to step back into the forefront, that's always an option.