I didn't even see jokiin tagged me but here is my setup he mentioned.
plus a more recent video that shows what it looks like from outside of the car.
The issues with my setup is blackvue cams have relatively low bitrate but for me personally I think it's good enough. Also the rear cams on both my models are 720p only.
I have considered many different options because I would love better quality but discrete formfactor is AS important as bitrate to me.
I love cylinder shaped cams like this though and the rear cams fit almost perfectly. I have been planning since I installed them to fabricate matte black covers to hide them better but NOBODY has ever noticed them as is which I find funny. Whenever I point them out to new people in my car they are surprised.
I uploaded this for my friends so it's unlisted but I don't mind posting it because it's funny :
One thing I've been concerned about is if my windows are open it makes me nervous having the cams on the edge like that.
I want to make a "sleeve" like Niko did for his rear cam DIY project recently.