I know, I know. You don't want a plan 'B.' You want acting to be ALL that you do. That's awesome. You also need to eat.
Nothing sucks worse than living out of your car. I know that Jewel did it. But you're not Jewel. (If you are Jewel, feel free to send me an email, I'd love to hang.)
You are, for the moment, an ordinary actor like thousands, yes, thousands of others like you. When you're scraping together to buy gas, or didn't pay your phone bill, or whatever, that doesn't really smack of professionalism now, does it?
Guess what? You need to have a little cash on hand to pay for parking, or keep your subway pass full. You need some money for a decent photographer. You need to be able to take a couple days off work to go shoot your friends short film that will, of course, win the shorts award at Cannes.
So, go find something. Waiting tables is the old standby, it's cash, and you can usually find someone to sub your shift. The only thing better is bartending, you're working basically the same hours, but get paid a lot more.
Getting a job to pay the bills isn't a plan 'B,' it's keeping your plan A alive and functioning.