The "Best option" is if all building have a line of sight and build a meshed point to point network.
You do not have this option as you have already stated that they do not have a line of sight.
Given this you next best option is a spoke and hub point to multipoint design
Root Bridge on the tower on the mountain with a omni direction antenna or a directional one if all of the buildings fall in the coverage area of the selected antenna
The one bridge per building.
If you expect a High level of traffic then you can start to break this down to smaller radio networks, up to 3
For example
Have root bridge number 1 on the tower using channel 1 and building 1 and 2 associate to this
Have root bridge number 2 also on the tower but use ch 6 and a different ssid have buliding 3 and 4 associate to it
Have root bridge number 3 on the tower using ch 11 and a 3rd ssid and have building 5 associate to it
Then break up your broadcast domain via a router at the tower site and the 3 radio networks in different subnets
For an even higher level of traffic then use a router at each of the 5 buildings so broadcasts on the buildings lan are not sent out the radio network and only the traffic that needs to.
As you can you can scale up your network as needed
