Wax is a good way to protect the clearcoat, but it is not a good replacement for clearcoat. But I do like the wax idea don't get me wrong. You want something with excellent UV protection, especially if the car isn't parked in a garage or in the shade. The idea behind Rebright is that its a one-time treatment. The factory headlights on Ford use a cheaper clearcoat that wears through pretty easy and doesn't offer the best protection. Sometimes it flakes of because its thermal expansion rate is different from the polycarbonate.
The Rebright is tougher than the stock clearcoat. It is actually cured and hardened in place by UV rays. It has the same transparency and index of refraction as polycarbonate, so it is truly clear, and the idea is it can last 5 years or more on one application, longer if you take care of it.