A wide angle of viewing means you're more likely to spot
obstructions in the monitor, particularly those that are very close and would normally be in your "black spot". But wider is not always better. In fact, going too wide produces a "fish-eye" image that will be extremely distored and very dangerous to use as part of a rear view or reversing camera system.
The field of view provided by the camera is determined by a combination of image sensor size & lens focal length. The larger the image sensor, the wider the possible field of view. However, a larger image sensor does not necessarily guarantee a wider field of view. Many rear view camera systems utilize a 1/4" image sensor, and provide only a 60 to 90 degree field of view. While a 90 degree field of view may be sufficient for some smaller vehicles, a 120 degree field of view is strongly preferred. You should absolutely avoid any system that produces lower than a 90 degree field of view. Most high quality rear view cameras that utilize a 1/3" image sensor produce a 120 degree field of view that is ideal for most applications.
Now, remember our first question at the top of the article? What are you going to use the camera for? This is where you need to think about the angle of the camera you select. Reverising and rear view is not the same. If you want to use the camera for rear-vision distance viewing instead of your big wide mirrors on the side of your vehicle in order to see behind your caravan, then opt for a camera with an angle of around the 90-95 degrees mark. Mount this one on the back of your van.
The ideal scenario is a two-camera system with a toggle switch on your dash to select the appropriate camera for your situation. For example, you could also have a wide-angle (150 - 170 degree) camera on the rear of your caravan, or mount this on the rear of your tow vehicle or have all 3 cameras!