+1 in Fritzhid post!!!!! As a journeyman electrician with 19 years experience I think you have some solutions, but 2 would be the easiest. up the wattage or add a few more lights. Your trying to light an area the size of about a football field. i am not sure how bright you want it to be but 5 light poles in this much area seems a little week no matter how bright the lights.