Few photos of the assembly of the "final product".
1. I soldered the grounding wire straight to the cold finger. Needed to hold the soldering iron on it for few minutes to get the whole copper plate hot. If you are doing this make sure that the copper is on something that can take the heat.
The other end of the wire is soldered to a small piece of copper with two holes that screw into the holder for the video board (which has been removed). See images 3 and 4.
2. Finger coated with Armour All Custom Shield (same as plastidip).
3. Sensor with cold finger showing temperature sensor ds18b20 and the small copper plate for grounding.
4. Camera insides fully assembled (apart from the back display).
More to follow but I took the camera like this (with back display mounted) out last night, i.e. without the peltier and cooler. I thought that the copper in the cold finger will provide some cooling of the sensor. I left it taking 3min exposures. Ambient was 10C, the finger/sensor was 16C, the exif data in the photos was 21C. Even without a peltier/cooler the finger made a huge difference.
Edit: test image is
here