Hey,
I just want to let everyone who might be interested in the furture know that the alternative route worked well.
That being said, the alternative parts were the most draining with little views and lots of cars (Hamnoroy) / bad road conditions (Senja).
It was still worth it, because the last part from Senja to Tromso is so beautiful!
About cycling in April: I obviously don’t have the comparison. It felt very special with all the mountains still covered in snow and with almost no other tourists (certainly no other cyclists). I was however really lucky with the weather, having lots of clear skies.
But note that in April you won’t have many options for stops. Some cafes, campsites and even toilets on the route only open mid may. I felt it was still enough, but would certainly bring my cooking supply next time 😉