You could try working in a hostel for room/board.
Beyond that, there are wo words that will be your friend(s): Hospitality Industry.
Bars and restaurants are likely to hire under-the-table workers if you have any type of kitchen or possibly serving/bartending experience. The worst that could happen is that you end up deported, but that's pretty bloody unlikely in the restaurant industry. I'm not sure exactly how easy it will be to get a position-- keep in mind that during spring/summer/fall there's a major influx of tourists and the unofficial job market will be more competitive.