I went to camping in the Alps with my piggie long ago; we had an igloo tent and the camping was at 1300mt (altitude); the temperature in the night was 8°C into the tent. I had a little baby and this piggie but we had the right equipment and nothing bad could happen about the weather. We stayed there 20 days.
The only issue is that during the day you are out for the trips and the piggie is alone... You cannot keep him into the tent, considering that under the sun the tent become very hot inside. You need to keep him outdoor... and the children of the camping will come around... That might be a risk; I used to leave my piggie's cage next to the tent of my neighbour who also had a pet.
Everything is possible, I started going camping in tent (mountain) with a daughter only 2 months old. But you have to think about everything, you should know the camping in advance, chosing a pitch with a bit of shadow and far from the passage of other people.