Bluetooth cameras

Caution: Wireless and bluetooth are not the same.

Also BT is somewhat more range limited than wireless due to power levels and protocol. Whether it can handle the distance and obstructed path from van rear to tug cab is something only trial and error will resolve, but I'd personally have reservations based on my BT experience.

Not a 100% test but, turn bluetooth on your phone and the car stereo, play some music then walk behind the caravan and see if it is still working. If it isn't then the chances of a BT camera working are pretty slim. If it does work it doesn't guarantee that a camera will work but it might have a chance.
Sort of a fail or maybe test.

The strength of a Bluetooth signal is highly dependent on the power of the device outputting the Bluetooth signal.

Bluetooth devices are divided into Class 1, Class 2 and Class 3 power classes. These power classes are not to be confused with Bluetooth device classes.

Class 1 are high power devices, putting out 100mW. Class 2 are medium power devices, putting out around 2.5mW - and Class 3 are the much rarer, very low power units, putting out around 1mW.

Thus, a high-power device such as a laptop or desktop will be rated Class 1, and put out a signal that can reach 100 metres - provided all the conditions are right.

Class 2 devices such as a lot of the smaller smartphones and headsets, are good for about 10 metres.

Some of the bigger smartphones are Class 1. The power output is directly related to battery size.

Class 3 devices are usually only good for about 1 metre and are not commonly used, unless the device is required to be miniaturised, and it can be kept in close range.

You can usually find the power output of your device by checking its specifications with regard to Bluetooth power output.

Bluetooth power classes

My smartphone (Samsung Galaxy Note 4 - Class 1) will still connect with my Hilux, even when I'm 50 metres away from it.

It gets annoying when it does - I have to make sure I switch off Bluetooth on my phone when I climb out of the vehicle, and stray many metres from it.

If you buy a Bluetooth camera that is portable and only powered by button batteries, don't expect it to have Bluetooth Class 1 abilities.

But if you buy a Bluetooth camera that is powered by the vehicles 12V electrical system, then you would expect it to have Bluetooth Class 1 power ability.

As always, check the specs when buying and ask plenty of questions, and get guarantees of performance in writing.

I have a trail camera that is supposed to be 20 metres range in infrared mode - it's lucky to get 6 metres.
The Chinese are good at overstating the abilities and performance of most of their electrical products.

Cheers, Ron.