You can dilute the juice down to 1.085 or so, where the juice from vine ripened grapes normally test.
If you use just water, the peach taste will be weakened, but the ABV will still be plenty high (for me that is... only you can say what is plenty for you).
If you use a bottled, or frozen concentrate, 100% fruit juice, it will take a lot more of it because it will test around 1.05 by itself, but by blending another fruit juice with your peach, the fruit taste will still be strong, as will the ABV.
Another whole primary fermentor may be required if you decide to dilute with juice!
But, such a blend could turn out tasting fantastic!
oxeye