Yeah, let's not do that... When I think of a Constitutional Convention, I want the document written by randomly selected citizens, whose work is then checked by another randomly selected group of citizens - rinse and repeat as many times as necessary. The process should be guided by members of the judiciary, whose sole purpose is to answer questions and serve as mediators - not to influence decisions.
We can't trust politicians or the rich with this process. The involvement of the citizenry at large gives the process legitimacy.