No offense but the key to getting your foot in the door is Say Anything (John Cusack reference). Open availability all minutes of all hours of all days of all nights. Anyone who says they are available ON PAPER more than you ON PAPER is worth more than you ON PAPER even through they might not be able to do a full Saturday either, other than ON PAPER. Understand?
Fact is... you'll never know what you'll never know until you get to talk to someone on the inside and in order to get inside you must be willing to promise them everything and explain any discrepancies after you're on board. Then explain to remain above board because you don't want to end up below board because that's equivalent to falling through the cracks of the boards. And don't even think about being overboard because that's crazy.
The key is to get inside. If you eliminate one of the busiest retail days (Saturday), then they have no choice but to red flag you into File 13 (trash bin reference).