If you are planning to use ham frequencies i would use some kind of x band repeater.
My be the solution might be 2m->10M and 10M->2m. Other frequencies can be used, but you have to check the local bandplan.
The input frequency on the airport side is a simplex frequency (use on as far as possible from the repeater frequency as possible) the second 2M rig is programmed with the repeater frequency.
By using 10M you will get better range for your linking especially if there is terrain blocking the path.
Use commercial gear and run no more power than what you require to get the link up and running. This will prevent the radios from overheating.
Commercial equipment is also more robust for abuse.
Motorola have some lowband VHF radios that can be converted to run work on 10M. The older ones are usually simpler to convert.
If you are not into electronics and computers it would be best to get the radios converted by somebody that knows how to do it. It is complicated. See http://www.batlabs.com/
If you are lucky you might find somebody here on Eham that can sell you the two radios for 10M. The 2m radios is simpler to acquire as there is a lot of commercial equipment for 137-173 MHz on EBay and similar sites. You will also have to make or buy some interface cables. If you use Motorola GM300 or similar you can get cheep cables of EBay for about 5$
Install the radios in pelicase or Zarges boxes http://www.zarges.com/en/packaging-transportation/boxes/
If you use Zarges boxes install a bulkhead connector for the antenna as you already got the groundplane in the box.
Have a separate box for the PSU/battery combo.
The PSU don't have to be able to run the radios if you set it up as a tickle charging, in a disaster situation when the power is unreliable battery backup is a benefit.