Winter driving in a camper is indeed doable.
The main roads are kept open all year, while some of the more spectacular passes are closed.
This is the map is updated and the best source for updated information. Unfortunately, it is in Norwegian language only, but this THE source.
https://www.vegvesen.no/trafikk/?lat=64.20937&long=7.82898&zoom=3&lag=Trafikkmeldinger,Vegkamera%20og%20v%C3%A6rstasjoner
As for spiked tires, most people drive with dedicated winter tyres without spikes. And rather than bringing snowchains, thei bring these;
https://www.autosock.co.uk/autosock-for-vans/
Actually, the spikes will only do you any good when on a hard icy surface. And in order to keep the spikes from being thrown out the rubber mixture must be harder, offering less friction on anything but hard ice and compacted snow. But if it makes you feel better, go for it.
The tricky part buying snow tires in central Europe is that the tires sold on the continent have a different subtance. They are made for mainly salted roads, better on wet black surface, useless on snow and snow covered roads.
One option is change tyres when in Norway.
Depending on how you want to get your Van up here.
If driving through Sweden, I would have changed the tires in south of Sweden, as there may be winter conditions allready in north of Sweden as well.
Taking the ferry, make an appointment when driving off the ferry. Get in touch with the Vianor company.
https://vianor.no/
(Most companies will handle english speaking calls)
Quite a few people use their campers in wintertime, so this should be an experience. Even the North cape is kept open all year.
In the south, the main roads are salted. However, when temp drops to -10, salt no longer works, so driving to colder areas, expect snow on the road. On the other hand, having proper tyres, driving on snow offers fairly good grip, and you will notice that the locals keeps the speed up. If that is outside of your comfort zone, use the mirrors and allow them to pass. Drive at your own pace and enjoy.
If you want to see the 'Nothern Light' this is more common as you proceed further north. I'm not saying you will not see it south of Trondheim, but don't bet on it. On the other hand, if time permits, dress up, bring a aluminum showel and continue northbound. Even if it is dark, it is not black dark as is common elsewhere. The snow will reflect the light, and on a clear night you see quite well. Some people find it rather magic, hence there are lots of tourists that now proceed northbound even in the winter (and the people from Asia think the Aurora Borealis is boosting their fertility).