Wow, I feel bad I missed this and didn't get you aknowledged earlier! Sorry about that! We were out of town, then things were just crazy! Two of my 6 kids just started school, 1 college, the others I'm prepping to homeschool, and trying to get everything put up from the garden at the same time! Anyway...enough about me & my drama!
I would probaly not try to can peaches w/o any sugar, just because the water would leach out sugars and flavor from the peaches and leave them bland. Light syrup should be plenty, though, and you might be able to lighten that, even beyond what they say, depending on your taiste. I've only done peaches and pairs a couple times, myself. You might be able to do peaches in a pint, but idk. It depends on the size of your peaches, I think. You could end up canning a lot of syrup and not a lot of peach, too. I'm not sure but if they might go mushy on youif you cut them up much, too. I don't know if that helps you at all, but at least now you know somebody read your post! :D