To avoid misleading, I should quote from the hardcopy about advance payment: "Payment for Overnight Getaway Attendees may be done in installments. Deposits of $25 per adult and $10 per child required. The balance is due by September 25, 1998. After that date space will not be guaranteed."
But if you read this thread and it's after Sept. 25, and you'd like to come, contact the fsgw folk anyway, and see if space still isn't available.