It takes a little bit of bravery the first time, but you can easily apply some force and bend the front rack stays to reach down to the seatstay. The rack stays are designed to be bent, and doing so doesn't appreciably reduce the carrying capacity of the rack. The majority of the load is carried down the vertical portions of the rack to the dropouts, and the horizontal stays are purely there to prevent the rack from rotating forward or backwards - their effect on the load bearing capacity of the rack is negligible. Many constructeur bikes do away with those stays entirely, bolting the rack directly to the rear fender.