I second all the folks who have said there is no workable alternative to registering the copyright. While affixing the copyright notice to everything you send out will establish ownership in the best case scenario, few such scenarios ever play out in a business where there's money at stake.
Having been involved as a witness and/or legal assistant in a number of copyright infringement cases for a 15 year period, I can tell you without a doubt that failing to register a copyright before submitting a song to publishers, managers and or recording artists is asking to be punched in the face.
It's not so much a question of whether you will prevail on your common law copyright claim in the end, but how much it's going to cost you to do so. As DCMaguire correctly points out, you can't recover damages in common law copyright cases. Common law plaintiffs often find themselves winning a case, but owing thousands of dollars in attorneys fees and costs out of pocket with nothing to show for it, but ownership of a song which may not have any further use for generating income.. But, in statutory ( having a registered copyright) cases you can not only recover damages for lost profits, costs, and attorneys fees, but the court may assess civil fines of up to $10,000 per infringement.