I've been looking into "dash cams" etc recently as I was thinking of getting one for mine. Halfords do the Nextbase range of cams and the "402g" (their top model) gets fantastic reviews online regarding set up and playback etc
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As far as I know they can be "hard wired" to the car so they can be left on either during the day in the works carpark(my case) or overnight(your case).
I'm not 100% clued up on it all tbh, however I'm sure a decent quality dash cam is what your after. It might have to be specially wired if you want it to keep running overnight etc though.