Thinking about blind side camera.

I think y ou can buy one of them small dvd player like screens.

When i looked into a backup cam for my car. The screens use the same rca cables tv's used to use before s-video and hdmi came out.

 

The "wireless" models have a very short operational range. Any real distance (more then about 20-30 feet) or metal obstructions renders them mostly useless. Also, they are easily scrambled with random electronic interference in the area.

 

Mostly true. Because most are wireless "open signal" 2.4 Ghz (because it is cheap to produce.) This the most used frequency in the country - security cameras, backup cameras, cordless phones, etc. For instance, I once tested one and was looking at the security cam inside a 7-11 store while sitting at a traffic light. Screen went back to the rear vehicle cam when I pulled away from the light. So like if you Google wireless vehicle camera or wireless RV camera, etc. - this is what you will mostly stumble upon. It is cheap, and it does work reliably for say 20-30 feet like you said, but that doesn't do me any good. In fact, we just ripped out and replaced an entire 4-cam system just like that 2 weeks ago. Driver had over $1000 bucks in it but it did not have recording capability and it blinked in and out randomly.
The ones that work reliably use "pairing" - just like you pair your headset to your cell phone. Only it's not Bluetooth - it's either digital pairing or IP. I have gotten over a 1/3 of a mile range in some unobstructed tests.
I have done a couple of oversize hauler flatbed's and step-decks recently where we did have to put a small external antenna "stub" on the back of the tractor to get around large chunks of steel (like hauling a Caterpillar tractor, jet engine, or other big, heavy metal loads.)

But there is wireless that works at more than the needed distances without interference if it is done right.

The bigger issue is actually where to tap into power for the camera and transmitter. You can use marker lights, but then they need to drive with marker lights on to power the camera. You can use battery, but you need to recharge the battery. We got lucky on some trailers that had "power on-board the trailer" (like reefers) but that is more rare.

At the top are some pics to visualize what I am saying.