Can my coverage be paused if I stop using my motorcycle for the winter, (or for any other reason)?

This is exactly what per-mile insurance is for! 

While your policy cannot be paused, if you don’t ride, you do not pay the per mile rate, and you have the option of removing any coverages that you are not using, (and that are not mandated by the state or a lienholder) - during that period of time.