I have mounted the DR650 front camera just below the front camera, and have no problems with heating or anything else.
Living in Denmark, and temperatures still only around 13 degrees celsius.
Camera not visible when in the drivers seat, and only slightly from the passenger seat.
The rear camera isn't visible at all.
Have mounted it in the rear window, and the wire is totally hidden - over the headliner and through the rubber tube with original wires to the trunk. Needed to cut off the connector and crimp/weld another mmcx connector on the cable.