if you get some early flowering plants should get it by the start of october.
the plants will show some purple/blue colouring from cold nights but should be ok.
would you be able to go out to the site everyday?
if so you could cover the plants and uncover them to put them into 12 hour light period.
could also try the auto flower plants, or low ryder's
but they get bad press from every1 who grows large plants.
would you be planning on growing every year if so you could bred seeds plants for what ya want.
i know sounds out there.
but if you plant late they will flower early but will be smaller plants
will add more later