If you are going to high altitude, you will run lean. That will get the engine quite a bit hotter and a 125cc will be struggling anyway up hills with a full load unless you just cruise. So just make sure you don't overheat and cook it. I assume you are sticking to tarmac with those wheels? Spare bulbs are essential too.

I don't remember you posting anywhere about this trip? Tell us more, sounds good. There's a great post somewhere about China V's travelling toolkit and bits and pieces. PM him if you can't find it, for a link. I will look for it myself later.