Your Focus is exactly the miss match that I mentioned. As said, you could install cantis and this is what I do when building a frame for drop bars that won't get caliper brakes. BUT if the frame is not set up for rear cantis then fitting a cable casing stop/hanger might be problematic. The seat binder might not allow a hanger to fit on it and there would likely be no barrel adjuster as well. The front hanger would have to clamp onto the steerer, not a bad thing just one more element to deal with when doing headset work and also this location for a hanger results in a very tightly curved/routed cable (think increased friction).

So when faced with your delima I suggest the Travel Agent solution. No further playing with make shift cable solutions, you get easy to adjust cables as well and they work really well (and have for 10+ years). The Travel Agents have a single pulley with two steps or diameters, not double pulleys. Just try to get the model with an adjuster. Andy.