I did something similar in using a drone camera however it doesn't use Wi-Fi. I did try a couple of different WiFi type cameras but couldn't stand the stuttering and latency.
I built my most recent camera car using an AOMWAY CMOS 700tvl camera with built-on 200mw 5.8 GHz transmitter. Next thing was to purchase a 5.8 GHz receiver with a standard composite output to a TV of your choosing. The image quality is pretty good and there is absolutely no stuttering or latency in the image. The downside is if the signal is interupted you may get some brief static, so throw away the stock antennas and pick up some nice clover style to maximize signal reception. I tested the range to about 150 feet (through a few walls) with reliable image quality.
The camera car is always a hit at the public shows even though it does look a little bit odd and patched together.
H1000
