I am sure the 'annexe' will be used this year, if you get no joy with the ACO, Page and Moy will start selling left over tickets in january.
A 3rd option would be to give one of the operators like Page and Moy a call (I have found them to be the most flexable in the past) and try to book your ferry thru them as a package, it may be a more pricey, but if you live in the tax free haven then there must be price to pay.