I assume this will be for client access, ala in a city or large human population center or wide open space? What country would this be for? Can you wire in most all the APs into some kind of city-wide fiber network? You mention mesh, but it's worth asking.
To be honest, creating those types of all-mesh/muni-mesh is not something we typically jump in to supporting, simply because it's a declining market that is very large on labor and cost, and are HUGE time sinks in design and planning, and short on revenue. There is a functional limit as to how much you can actualy backhaul over the air from a deployment of that size, as well as a functional limit as to how many APs you can deploy in the same area (wide open spaces) based on the number of channels in your area.
A good rule of thumb is that as many APs as possible should be wired in to a wired network. Any mesh should be as minimal as possible and usually no more than 2-4 mesh APs per gateway. You would need approx 6-8 APs per sq km doing mesh (depending on topology and environment, it could be more), and figure a cost of approx $3k (US) per pole for equipment, labor costs, and time, which means ~$25k per sq km average, and at 100sq km = $2.5mil in install and equipment costs alone, ignoring any design work, planning, time involved, survey, etc. On top of that, the easements and utilities To be honest, those deal rarely materialize, so when these opportunities come up, we leave it up to the intergrators/partners who wish to pursue these kinds of opportunities, or refer to known partners with a very strong background in this type of deployment.
The best place to start is the Ourdoor MIMO VRD (http://community.arubanetworks.com/t5/Validated-Reference-Design/Outdoor-MIMO-Wireless-Networks/ta-p/155624) as it has all the information you would need to get started and covers everything from survey to design to caveats to architecture and topology.