I think video chips cannot tolerate high temperatures. In some reviews, owners complain the camera overheats and stops video recording. A standard dash cam cannot operate above 140 F and some cameras exhibit degraded performance at lower temperatures. The front windshield is exposed to mid morning direct sunlight which is not recommended. The rear windshield is exposed all day. I performed this Google search "what is the highest temperature dash cam can withstand".
I'd worry about the thing not being defective and stopping recording without you knowing it before I'd worry about ease of removal. I understand that's what you're trying to prevent but most (yes, literally most of them) are crap even if kept cool.
You should be able to remove most dashcams with little hassle. What I would be concerned about, how would you keep the dashcam holder glued to the windshield? I am in NY and I had a tough time until I used Superglue.
I have Rexing, Ausdom, and StreetGuardian. Out of these, only StreetGaurdian has a kind of 'lock', rest are easy to remove.