I'll go with you to Trondheim IO if you want to share the ride
The weather in Bergen is typically !!!!!e, I think last year they had about 80 consecutive days of rain before Christmas. However if you entered Norway further south (South of Stavanger) in my experience the weather is much better (and the terrain is flatter). Then you could head up the spine of Norway inland a bit where the weather seems to be better....
I didn't realise but the highest mountian in Norway is only about 8000' I think....