AUTO-VOX M1 Car Backup Camera Rearview Backup Camera Waterproof Night Vision Kit,4.3'' TFT LCD Rear View Monitor Parking Assistance System with One Wi
https://www.amazon.com/dp/B071D9TWSG?ref=yo_pop_ma_swf
I use one of these for reversing. Mounted on right of dash board. Cable runs down right hand side of the van and takes a feed from the reversing light at rear light cluster. Originally I had the camera mounted under the bumper but you really need to be looking down on the bumper to get some perspective on the distance from the bumper to the obstruction behind. So for now it's temporarily mounted on the light cluster. I'm planning to hide the camera inside the tailgate spoiler in the near future.
For a dash cam I use an old Samsung S3 phone mounted on the dash, running Autogaurd app.
A fair bit cheaper than 700 quid.