, as I understand, de-jure foreigners may not go to Medium and Rybachiy peninsulas, but de-facto - no one will check your documents. You risk 5000 roubles fine or deportation. Let it bring some excitement to your trip!
Here is the link to Russian forum: http://www.moto-travels.ru/forum/11-2328-1
If you will need any translation - let me know.