First off, address those loose mirrors, That's sorta a safety issue..
As far as camera systems, there are some good kits out there.
I've owned a few of the really cheap Chinese b/u camera kits and (for the obvious reasons) they never seemed to hold up. The displays are the usual failure point over time but I've even had the actual cameras fail.
For this truck I decided to build my own, There's really not much to these camera systems.
1) camera(s)
2) monitor that can support x-number of inputs (ie: cameras)
3) and an optional recording medium (that can also be used to expand the number of inputs and how they are displayed)
Cameras are pretty generic. Each needs 12v power and a wire to send the image to the display, but that's really it. No moving parts to fail (but they can still die on occasion due to impact or environmental damage). Most cameras output will typically be compatible with RCA/AV connections (and the 4-pin wiring is slowly becoming more the standard). IMO (20 years in IT), I much prefer wired solutions over wireless. Wired is as bit more installation work, but not much (you still have to run power to each camera anyway). Being wired removes a lot of the issues that inherently come with wireless devices/communication (disconnection, signal loss, interference, etc).
Monitors are often where companies cheese it with the cheap stuff in the kits. They tend to be quite small (by my standards) with really poor quality and resolutions. I much preferer a minimum of a 10" display (currently have a 12" monitor for my camera setup). The only caveat to consider with the monitor is the number of inputs the display has (which can dictate the number of cameras supported by simply plugging them in). If a monitor has RCA/AV, HDMI, VGA inputs they can all be used to connect a camera. And depending on the monitor they can often display all the inputs in split screen. But for a single camera deployment or one with a DVR attached, pretty much any display will do. But IMO, the more cameras you add the larger you want the display (four postage stamp-sized images on a six inch display really won't help your driving).
If recording is an option you feel you
don't really need, you can stop there. All that's really needed are a camera(s) and capable display.
If you want recording, there are actually a couple of options. The simplest being a small 12v DVR . Most all of these designed for vehicles will record to memory cards. And if your monitor only supports a single input, a multi channel DVR (ie: a security camera recorder) can often expand on the number of supported cameras.
No real point to make here. There are good kits and bad kits out there. It helps to understand the components. And those components can be replaced, upgraded, etc. You may want a larger display, or three cameras of a specific mounting nature. Perhaps you need a recording function. All of these things can be purchased together or separately, added to, upgraded, or expanded upon.
I'm personally not as interested in side views as some folks are (I'm more dependent on the mirrors). I only have rear views for now but it can switch cameras after the trailer is connected (it has it's own camera). But I will be adding cameras to my remote spots when I get them mounted. I'll likely toss in a DVR at that stage so I can monitor thigs from either cab or habitat.
random links
Cameras
Monitors
DVRs
Any 12v DC recorder will work, btw. So if you needed months of security/driving footage recorded or 16 camera input, it's easy to achieve.