lemon and other citrus fruit peels are composed of 2 parts, the rind, and the zest. the rind is bitter, and the zest holds strong flavor and sent of the fruit in the essential oils. you can use a carrot peeler, or a fine cheese grater, or ideally a zester to get the zest off of the whole citrus fruit. this zest can be used for flavoring without the bitterness of the peel. if you have a small distiller setup and know how to do it you can easily also make pure essential oils from the zest, though im not sure how you would combine the oil due to the fact it will not mix with water.
just thought that might help you out. please report back on how the hard lemonade goes, I havnt seen too many good recipes out there and im looking for a really good one.
best of luck