We too are looking for the highest and most solid infrastructures and water towers are definitely on our list. Sometimes just a solid building is the answer offering a big flat roof for truck batteries and solar power to support power backup.

Hurricane Katrina had two problems. Twisted wireless communication towers and power outages due to floods. Either one will kill your network.

WiFi/WiMax lower powered radios seem to be the only survivable wireless topologies that have survived hurricanes. In general you can get four months of radio power out of two truck batteries even without solar. WiFi/WiMax Wireless radios and antennas also have a small wind profile. All you need is a good physical structure to bolt them on to and they will survive as long as the building does.