I have mine into 12v socket on current car then tucked behind glove box and with an extension lead. It is just tucked into edge of trim up door across where this is a jin in molding and around window pushed in with a plastic spatula so only bit of cable visible is where it comes to camera itself. Cable can be pulled out with no tools required.
is that photo showing your cameras on the right hand side of the mirror, if yes that is illegal. As you can see it and watch it, if involved in an accident they will immediately say you were distracted by the dash cam. It must be fitted were you the driver can not see it.