You don't know what your missing until you hop into someone else's rig and they don't have a trailercam.
So what is a horse trailercam? It's either a wired or wireless wide angle lens camera that projects to a small monitor in the cab of the truck allowing the passengers to keep and eye on the horses while on the road. Now that I have one it makes trailering so much easier because I am not constantly worrying about every bump I feel from the trailer. All I have to do is look at the monitor to know that everyone is OK.
The desire for the trailercam started when I was hauling horses back and forth to local shows. These specific horses were not in a trailer that often and so they were usually pretty fidgety and the Thoroughbreds didn't like to just stand so they always seemed to be off balance, which meant I was constantly feeling movement from the trailer.I looked at the packaged trailercams like those on some popular horse supply sites, but I just couldn't bring myself to spend hundreds of dollars on a camera setup, so in true Fred Smith (my father) fashion, I tinkered something together.
I started looking for wide angle cameras which could be used in a variety of light situations and with a wireless signal strong enough to work through the aluminum of the trailer and the cab steel. After 3-4 unsuccessful trials with products from Radio Shack, Walmart and Kmart, I purchased a backup camera package for cars, trucks and RVs that I found eBay. The package included two wireless weather resistant cameras and a black and white 5.5" wireless TV/receiver. I believe I paid about $150 three years ago for the package and the prices seemed to have dropped even more since then.
To install the camera, we cut a small hole in the the wall between the tack room and the horse stalls and TJ wired the camera power into the trailer wiring. The rest was just a matter of plugging the 9v cigarette lighter powered TV into the cab. The setup worked really well and was not the $600, $800, $1200 for cameras designed specifically for a horse trailer. I decided not to install the second camera because the first one had such good coverage.
I admit that the monitor that came with the package died after a few months so I went back to Walmart and Radio Shack to see what I could come up with. I ended up with a 9v battery powered Astak wireless camera system for $70 and a portable DVD player for $80 from Walmart. The Astak wireless AV receiver plugs into the DVD player and they run off a 9v splitter that works off the cigarette lighter. It's probably not as pretty as the expensive systems, but it works well and even with my detour after the initial monitor failure I am still well under the $600 trailercam price point. A pro to the monitor dying was that I ended up with a smaller, lighter monitor (DVD player) and I can use it to watch DVDs while sleeping in the trailer at horse shows. 
