Yes I do think your runs are too long. You could install an inline duct fan that would help.

The lights should draw air from outside your room and exhaust the outside as well. You should not be exhausting the air from your lights inside your room. Keep the run's short and as little bends as possible. You should only need to run your exhaust every 6 hours or so if you are using CO². A mister will help to keep the temperature down and raise the humidity and that's good for plants.