I can see that this would be very problematic, but I'm not sure that there is much relief for you in sight.
The right of way (also called an easement) usually "runs with the land", which means that when the right of way was sold to the lumber company, the right to use that access route became permanently attached to their property, so that prior owner and all future owners of that property would retain that right of access.
If you haven't done so already, you should review the language of your easement. Although it is unlikely, it still is possible that the right of way was for that one property owner only (the lumber company).
With all that given, it seems arguable that the use by the neighbor of the right of way as a snowmobile course is a use not contemplated by the right of way. In that event it is not really being used for ingress/egress, but as a recreational track, and their use of it in this manner is a nuisance. Unfortunately this would require a lawsuit to pursue, but you may have a basis for asking a court to limit their use of the right of way to traditional ingress/egress only. Short of going to court, there isn't a lot of leverage that you can pull in that regard.
One thing that you have to be careful about is that as the property owner you do not have the right to obstruct their use of the right of way. So if moving snow into the right of way obstructs the neighbor's access, the court could rule against you there. My main concern here is that if you decide to go to court over this, you want come in with "clean hands" so that there aren't any issues that the neighbor can hold over your head in front of a judge.
Perhaps with a lawsuit pending which alleges that their use of the ROW as a snow mobile course is outside of the contemplated use of the ROW and is a nuisance, you might have more leverage in convincing them to sell the ROW back to you.
I wish I had stronger options for you.
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