What I recommend is that you stop being a lazy arse and get a 2 camera system.
One for the front and one for the back, this IMO is the minimum essential setup.
It can either be a dual camera unit or 2 single ones.
2 singles can IMO be better as a dual unit usually has a lesser quality for the rear.
They can stick to the screen using an adhesive pad, much better than the suckers.
The power cable can be fitted behind the roof lining, down the frame behind the plastic moldings and then into the aux fuse area under the dash.
Stop being a lazy arse and get the right one.
Mine was only £40 (now obsolete) but does record good quality images.
Also get one that can accept 60-128gb+ memory cards, bigger for the higher quality recording.
takes about 30 mins+ for you to install, once done just forget about it apart from occasionally swapping the memory card while you download recent videos for youtube