I spoke with a local Seattle company that does Russia visas, and received this response:
Thanks for the additional information. I just spoke to the U.S. office manager of a Moscow-based company that we work with for booking travel arrangements within Russia for our clients. She seemed to be quite sure that the entire Kamchatka Peninsula, where Petropavlovsk is located, is off-limits to foreigners. I explained to her your plans and she said if she would try to find an alternate refueling point. I’ll update you when I hear back.
I noticed this is a different E-mail address than the one you gave me on the phone so I am copying in the other one as well just in case.
Rainier World Travel Inc.
I sent them the cruising logs from a couple other boats I’ve found that have made the run, and they agreed to push harder.