Thanks for your reply and for the couple of links to similar ideas projects.
I've taken dark photos at different exposure length and will be including them at the end. The jump in thermal noise increases with longer exposure, quite significantly. But it was quite warm where I did the test. The ambient temperature was 30 degrees and the sensor was about 40 degrees. I looked at 2 different images of 120s exposure with a difference of 2 degrees and the thermal noise is visible without having to zoom in.
I'm printing my final design for the case, I'll try and mount everything tomorrow and do some test before the end of the week.
I'll put a small desiccant pack inside the camera if condensation is a risk
