Hi!
I would recomend Telemark as one of your stops. Here youŽll find the "Telemarks Kanalen", were you can take a trip on one of the boats that still bring passengers from Skien to Dalen. This trip will take you through several locks ("sluser") as the boat is lifted from sealevel in Skien to approx. 80 meters by the time the boat arrives in Dalen. Most people take the boat from Skien to Lunde or v.v.
Telemark has several airports of varying sizes. Skien (ENSN) and Notodden (ENNO) are both AFIS airports with asphalt runways, while Lunde (ENLU) has a grasstrip 700 meters long. A Cessna 172 will have no problem here as long as the ground is not too wet.
Remember to check in advance with the locals..
Lunde is a great base for hiking with "Lifjell", a mountain approx. 1000 meters high, just 15 kms away, and for the telemark canal. The canal flows right by the airport.
Just PM me if you would like more info!
BR
Buster