I hate to kick up the old "rehydrate vs. sprinkle" debate, but you should be fine with 1 pack even if you don't rehydrate. A lot of the side-by-side comparisons I've seen are fairly ambiguous over which method results in a better tasting beer. In my limited experience with beers similar to the one you're planning on brewing, sprinkling 1 pack of dry yeast has given me clean, tasty beer with no off-flavors.