I will be the one to disagree with the others! I am bias, because I sleep exceptionally cold.

You stated that the AVERAGE temperatures go down to 5C. Your sleeping bag's low rating is 2C. The sleeping bag ratings assume that you have an adequate pad. Microclimates while backpacking are often less than the "average" temperatures. As for extra clothes to put under the bag, if you have lots of extra clothes, you are then taking too many clothes. Better to take a better pad. I rarely have extra clothed to put under me - plus extra clothes are really lumpy!

The r-value for a pad twice the weight is more than twice the r-value of the lighter pad.

As far as more sunlight in Scandinavia- does not matter how much sunlight if you end up getting no sleep due to being cold, whether that is 3 hours a night of 8 hours a night.

I would buy a new pad that is between the 1.7 and 5 r-value.