I myself rock the Rexing V1LG in both my Mustang and Boxster. It is a loop recording unit, but it records up to 48 hours before looping. It also has GPS impact reporting, and an internal battery. Lets say your car is sitting, if some one hits the car it pops on, logs the GPS, and records the event. Also it will not record over events. It also has an event button, so lets say you see some one get hit you push the button and it records it as an event and will not record over it. I have both of mine tucked up behind the mirror. From inside the car you can't even see it. The rear camera is attached to the roll bar on the Boxster. That is noticeable with the top down. But it doesn't bother me.
Word of warning though.... Never use your dash cam's recordings to prove something your wife said..... It won't end well.
https://www.rexingusa.com/products/rexing-v1lg/?from=products