Johnny
My approach would be to turbo nozzle, if dirty - moss, algae growth, black spot but if it is just general grime i'd go over it with the FSC and rinse off, spot removal.
Chuck a load of sand down and brush in - when dry.
How long is it going to take you, from your previous experience?
How much travelling there and back?
What do you want to earn, against what you earn on the glass?
What can be achieved in a day is a massive variable, some might be able to get through that in a day, others may be a couple of days.
Put a couple of pictures up and let people see
Rob