What to Include in Section 988 Opt-out Document?

I began trading spot Forex in February and have been quite successful thus far; I will owe several thousand dollars in US federal income tax for 2017. In 2018, I project to make significantly more from currency trading, and as such, I intend to opt out of section 988 and elect section 1256 for 2018. From what I understand, I should prepare a document indicating this election and have it notarized prior to January 1, but that the document is filed “internally”; so in other words, I simply keep it as proof of my election in case of an audit.

My question: what language should I include in this document to ensure that my bases are covered? Is it as simple as “I, (name), opt out of section 988 and elect section 1256 for tax filing purposes in 2018“?

A web search returned a lot of articles citing that this document is required, but there doesn’t appear to be an official form, and I couldn’t find any examples.

A follow-up question: is it worth having a tax professional advise me and prepare this? If I meet my projections, I plan to use a professional service when I file my 2018 taxes, but I’d rather not spend money unnecessarily this year.