What happens to the hotspot if you're driving through an area with dodgy reception? What happens when the cloud camera can't dial home?

Rather than trying to link together wireless devices, why not just get a rearview monitor kit with a wired rear camera that you can relocate anywhere in the car as needed? Here is one for under $40 that has a waterproof HD camera with built-in LED lamps and a 2-year warranty.

https://www.amazon.com/LeeKooLuu-Monitor-Waterproof-Reverse-Continuous/dp/B06XKPQ6YZ/