Several years ago I bought a BlackVue dash cam for my BMW we use for road trips. It was great. Uses a small micro sd card that can be easily removed and viewed or copied. It has WiFi so you can view it on you smart phone. It has GPS and an array of other features and it gives you options of what you want to activate. I was so impressed that over the years I have added them to all four of our cars and three of the kids cars.
For the Boxster I hardwired it by running the power across the header and down the right side A-pillar. From there I tapped into a switched power line behind the radio. (Another old age moment.... I can't recall which line I used.)
I only have a front camera in the cars though they do offer a 2-channel. Like all consumer electronics, these are getting better and cheaper.
IMHO, the BlackVue Wi-Fi DR500GW-HD is a great unit.
