Do a compilation on an SR form (essentially combining several songs) which will give you protection for the number of songs you send for the cost of one ($30now?).
It's yours whether or not u send it in to copyright ofc, you just have to prove it. I'm sure you've heard of poor man's method but with the digital age, it couldn't hurt to email yourself a copy.
Or, save yourself the effort and $ by giving up on the dream of becoming a hit maker like I did many years ago and pursue other avenues to fame. I'm sure you have other means of expressing your artistic side. Gay porn? Polka? The list goes on, you just have to find your reason for being born.