You may want to look in to the ubiquity equipment. I manage a large HOA that is about 69 Acres. We are using the opensprinkler devices to control our lights and irrigation and security cameras. I have slowly been building a wifi mesh usiung ubiquity radios that have LOS of 7KM. Believe it or not these devices are about $60 each and they have worked very reliably even in a dense areas.