I'm following most of this, however, I'm fairly certain you only have three years to revise a return. Also, I've done so several times and it's no fun. Finally, if the IRS decides you owe back taxes for taking a deduction they don't think you deserve ,the penalty is usurious.
I've always made it a policy to overpay taxes while we hashed out a solution. When I've prevailed, I've even gotten back interest.