Just checked Booi's brochure and prices were listed by the day. Nothing was mentioned about arriving late and spending the night at a gotcha rate. The charge could be justified if you had an unscheduled flight for your convenience and the plane returned to Red Lake empty. Flying costs are expensive.
In May our guys went in the night before, fished about 5 hours, and were not charged. Also 7 of us stayed an extra day to accommodate the flying schedule and we were not charged for the extra day.