Because I already did what U plan to do, need to tell you that unfortunately high-speed wifi link is only a dream, there is no possibility to do this.
My setup was 
GCS - Airlive n.power (30dBm), Yagi antenna 18 dBi.
PLANE: RPi with Alfa 036 -unblocked, 33 dBm with 5 dBi omni antenna. The power for wifi card was taken from separate BEC,
Link /: telemetry and video simultaneously.
My attempts
And another one:
we discovered, that with real conditions max wifi range was about 5km, mainly because of other wifi jamming on the same channels.
on these movies we were flying about 700-1000 meters and during turns we had problem with video.