Do they mind if you wear a few extra clothes on to the plane so you can cram more into your carry on Personal Item bag that's free? If they don't, you might be able to take a lot more stuff with you. I heard there were people selling jackets specifically designed with huge pockets for airlines like this. But when they pat you down at the gate, it might raise eyebrows and Spirit has stiff charges for baggage needed at the gate. I'm thinking this is what those gate charges might be for.