Ask your boss for a leave of absence. You'll have the security of returning to your job, but will also have the time to dedicate to your new project. You say you can't support not having a job, but if push came to shove, could you not work for 3 months and support your family if you cut down on expenses? If you are a dev at a-list startups as you said, you could probably pick up a contract here or there.