Years ago when my husband joined the Peace Corps, he had not heard about PSLF and did not necessarily plan to work with the government as he currently does.
He thought it would be best to put his loans on deferment and pay off the interest while in Peace Corps. Later when he got hired with the government, he was happy to hear that Peace Corps qualifies as Public Service Loan Forgiveness, but because he had deferred his loans, those months did not qualify. Neither FedLoans nor Peace Corps gave any guidance on the matter.
It turns out, that what you need to do is sign up for Income Based Repayment while a volunteer, and because PCV's earn no income, their monthly payment is zero.
Those zero dollar payments DO count towards PSLF. Please keep this in mind if you are joining the Peace Corps, whether you plan to work in public service or not. Sign up for income based, just in case.