First Student Housing Development

I'm working on our development groups first student housing development and we are trying to get comfortable with the income at stabilization. I built a proforma after speaking with a few property managers, but the operating expense ratio seems low to me. I've been told a good rule of thumb for student housing is 28-32%.

Is that what you guys have experienced?

102 units with 200 beds

Any input from student housing developers would be MUCH appreciated. Also, any thoughts on the value of hiring a consultant to tighten up my numbers? I'm a little hesitant of consultants accuracy if they don't have continual direct experience.

Thank you all!