30 rooms is probably more like 50-100 attendees, with double or triple occupancy, and accounting for some couples attending where just one half of the couple plays.

Personal thoughts:
$109/night is more feasible for me to make it. $75 attendee fee is pretty high, especially in combination with a high room rate. Will you knock anything off for GMs or volunteers? Will you have a VIP package (I once booked the VIP package at a smallish con which came with con badges, a little swag bag, and the room rental and was utterly stoked because it meant I didn’t have to fight over the room). Do you plan to run a Kickstarter? Will you have a safe conduct policy?