Your best bet is to get one of two different types of rear view cameras. One is featured in the how to section using one of the inexpensive units from Pep
Boys here in the U S. It can be mounted anywhere you want. Down next to the bottom of the rear clip or mounted as a third brake light on top of the spider. The camera is a tiny unit about a half inch tall and can be mounted inside the third brake light housing. They are designed to go on the license plate. Should give you a good range of vision. They are wireless, so all you need is power to the camera and to the viewer. The viewer can even be plugged into the cigarette lighter/auxiliary power outlet
Your other choice is to go with the bullet cameras or other rear view camera and a flip up stereo unit. These units all accept the rear view cameras. The screens can be anywhere from 3 inch to 7 inch. Units cost in the $250 and up category. Look on Ebay for tft stereo. There are name brand units like Pioneer etc. Some have TV, GPS, mp3&4 capability, bluetooth etc. At least that way you can justify the expense. While your sitting on the grid, you can enjoy a good DVD while waiting for the action to start.
tft stereo, Car Electronics, Consumer Electronics items on eBay.com
A word of warning, The different sanctioning bodies require outside mirrors for competition. They turned me down when I asked. Personally I don't care for the side mirrors. With the camera, you look in one spot for the chasing traffic, not two.
Bill