Altiplano? Northern Peru?

When I traveled South America, I encountered significantly colder temperatures climbing from Arequipa to the Altiplano and then across Bolivia. Not quite as cold as coldest you list but still -10C overnight and below freezing starting in the mornings. I stayed low along the coast until southern Peru. A few things I learned for me:

1. Overnight is coldest. I ended up with a second lightweight sleeping bag that I put over my normal sleeping bag (rated for -5C). I needed to make sure to camp where I could block a cold wind. I found inside shelter one of the coldest nights. When camping below freezing I kept a water bottle in my outer sleeping bag to keep from freezing.

2. Riding during the day. Waited until the sun was a little higher and it warmed. With my gear I noticed a cutoff around -4C where I had difficulty keeping hands/feet warm enough with my gloves so minimized time riding colder than this.

3. Moisture. In general where I went was a very dry area but I'd first understand if those ice/snow in forecast is actual precipitation. If so I'd time things to cross coldest passes with sun and not ice/cold. More because of temperatures or risk of getting wet/cold than traction. As far as slipping on surfaces particularly with ice; simple light snow and climbing one can ride. Ice itself I would avoid riding unless you have studded tires (which might be tough to come by).

4. Limits. I would have thresholds of cold where I'd avoid camping and different thresholds I'd avoid riding. In those cases, if necessary I'd either take a different route or time things to avoid worst days or use transport such as a bus to skip past.