I can't help with specifics, but I worked in Oulu, N.Finland some years ago.
A few general points... the seasons in Finland seem quite defined, so winter lasts till... then suddenly it's spring... etc. It's absoultely freezing in winter, but I've been to the Arctic circle in June when it was 32 deg C !
It is a big country with very little in it. As I said, I worked in Oulu and I would recommend it. It is fairly self sufficient and you will find everything there that you might want. It also has a large level camp site an easy walk from the city centre.
You can get a train from there to Rovaniemi on the Atctic circle where you will find Santa Claus's official village. You can visit Santa all year in his air conditioned 'grotto' and even write Xmas cards which are forwarded in December for you.
In summer you will find some unusual sports like 'Wife carrying', midnight golf and of course, the world 'Air guitar' championships - held in August.
A beautiful country, but a bit pricy.
------------- Two drifters off to see the world.
I'm tired of reality, so I'm off to look for a good fantasy.
Could be worth checking the freight ferries routes and see if any go to Finland. One of my friends used to have family in Sweden & used the DFDS feight ferries from Immingham (near Grimsby) to go over with their campervan. It wasn't cheap but it did cut out a lot of driving. Hope you manage to get sorted
If you use a Gaslow system for your lpg, fill up before arrival, filling point's are few and far between.
The Ferry from Turku,Finland to Stockholm,Sweden (1000 islands ferry) was an enjoyable way to travel during the day (11hrs) the weather was kind to us, sunbathing on the top deck! and a good rest from driving, cost's roughly the same as diesel when driven.
It's a long drive to Finland, but worth the stopovers in Germany, Denmark and Sweden enroute.
For us Sweden take's some beating for Motorhome travel and stopovers, especially in the tiny villages.
Hope you have a good trip.