The Link Budget exercise that you have undertaken will give you the
distance you can transmit/receive, assuming the following:
1) Line of Sight -- No obstructions in-between transmitter and receiver
are assumed in the link budget calculations. This of course becomes
increasing difficult as distance goes up, and tends to require that the
transmit and receive antennas are placed higher and higher above the
ground. In addition to Link Budget you may consider calculating the
Fresnel zone to get an idea of ideal height of transmitter/receiver at
various distances if you are looking at long haul applications.
Example:
http://www.afar.net/fresnel-zone-calculator/2) Fade Margin -- I did not see you mention any fade margin in the link
budget calculation below. Always a good plan to build some margin or
safety factor into the equation to see what kind of link you will
actually get. RF will fluctuate and so building in the margin will
compensate and ensure you get your desired signal, or better at all
times during the day.
If you have clear line of sight, enough height to clear
obstructions/Earth, and some margin built into your planning, distances
like you have mentioned would be achievable. That beings said, for
every long haul application I have seen to date, there are many many
more that are much more straightforward to deploy (e.g. connecting
buildings across the street, across the parking lot, across the soccer
field).
Rds,
JF