If the problem is that there are no holes for the rack near the dropouts, get longer bolts so you can use the mounting holes for the fender stays. I dont know what rack provision there is at the top of the seat stay, but if there are no screw holes, get P clips from the hardware store. P clips work fine for this as they dont carry the weight of the rack and its load, but only stop them from rocking backwards or forewards. The nicest rack I have seen in Canada is the Radical Explorack (about $45), which has tubes shaped to prevent the bags swinging into the rear spokes and is a bit longer than most racks, so you will be less likely to have your heels hitting the front corners of the bags.