Why not just take a week off unpaid? If they pay you well enough for the trial week (which they should, since this is technically a one week contract, and thus

Why not just take a week off unpaid? If they pay you well enough for the trial week (which they should, since this is technically a one week contract, and thus a contractor's hourly rate is higher than an employee's) then you could reason that you're making more money without sacrificing your vacation time - you are allowed to take vacation time and not be paid.