This is a truly unfortunate arrangement. One of the better parts of
theatre is that it is such a collaborative effort. From an educational standpoint, your institution is not emphasizing one of the more important aspects of
theatre, that is proper communication and process.
Your starting
point should be with the head of your
theatre program, whether that be your
theatre teacher, club adviser, director,
etc. Explain to them your desire, as a group, to improve your contributions to the production and wanting to take things to the next
level. Offer some examples of points of concern from previous productions that could be improved with the addition of a
stage manager. You will, of course, want to do this at the appropriate time. Do not do it just before tech, in between classes, or in passing. I suggest do it at the beginning of a production cycle so that the
stage manager can be incorporated in the rehearsal process, as is standard. Include any other adults in the conversation as well, such as your TD, other director(s), advisors, administration,
etc.
Good luck with it!
~Dave