I think whether its a good topic or not is dependent on what aspect of schoolies you are focussing on. how are you gonna gather primary information on schoolies when you won't be able to expereince the actual event until after the PIP is due. there are a lot of issues you will have to consider...
I think that its definately an interesting idea - and no i don't think its too inappropriate (as long as you treat it from a 'social unquiry' perspective). however i'd be careful that its not too specific. maybe you could look at social norms in relation to dress codes for each gender in general...