James, the video is broadcast over FCC legal frequencies, primarily in hte 1.3ghz and 5.8ghz ranges.
1.3 ghz has much better penetrating abilities however 5.8 is a much smaller and lighter system.
I have used the same set up and it broadcasts extremely well, it does suffer from shadowing, however I think on 99% of kart tracks (relatively flat, and not blocked by a mountain) it should work fine. I might be slightly concerned if you were in the last motor home in back of the pits, however with the reciever antenna ontop of a tent or the motorhome it would recieve just fine.
I will be testing further this weekend if all goes well.