Mechanical cameras in cold enviroments

Need some advice on bringing some cameras to some very cold mountains

I'm doing a hike in Nepal across the Annapurna mountain range. Will be going end of march/start of april. From everything ive managed to read temperatures can get as low as 10°C and 0°C at night.

I plan on bringing a Fujica GL690 and Rollei 35S. I was wondering if anyone has had experince shooting on these types of cameras in these enviroments? And advice or tips would be incredible!