I buy a top of the line luxury boat & charter it out one week of the year, because I need exactly that much income to make ends meet, would my purchase qualify for the business exemption?
You'd get a proportional exemption equal to your business usage. In this case, it sounds like the exemption would be 1/52nd of the total.
You would collect the FairTax on your charge for the charter, retain 1/4 of 1% for yourself (your fee for collecting the tax) and forward the balance to the State Taxing authority.