Rather than a bale of peat, get a bale of promix, which is essentially peat that has had the pH and drainage improved with the addition of, resp[ectively, lime and perlite. Peat has antiseptic properties and should not get weird on ya in storage. Addition of some myco-stim might not be a bad idea though; inoculating it with GOOD soil fungi is good for your plants anyway. But I have never tried to store peat or promix over long periods of time so I'm not sure.