Just do what everyone else does. When December rolls around, go buy a bunch of sheets of the "Forever" stamps....I still have some from the last time they raised the prices, so that just goes to show you how much I snail mail stuff.
Oh, and a little tidbit of info if you didn't already know - all of the rural route carriers are subcontractors for the government. They work for themselves, so the post office doesn't have to pay anything in regards to health insurance, unemployment insurance, retirement, etc.