I did something like this just recently. I needed to get audio to a point 800 feet away from the source. I used an AKG IVM4500 transmitter and an AKG SR4500 receiver. At the transmit side, I had a 6-element home-brew Yagi antenna up about 10'. At the receive side, I had two AKG passive paddle antennas up at 10'.
With the transmitter set to 50mW output, I had just a hair under full signal on the meter at the receiver. The audio quality was excellent and there weren't any dropouts.
I believe this set up would work reliably over 2000+ feet as the transmitter can be bumped up to 100mW of output power.