I think pad life is dependent on the compound, weight of the vehicle (your RX-8 sits at around 2800-3000lbs), and how hard you are on the brakes. If your pads are not designed for high temps you I would expect them to wear a lot quicker than a dedicated track pad. Hawk offers a variety of pads from daily, street and light duty track, and dedicated track pads which range in heat temperatures. Below is a chart that shows their line up and respective heat ranges.
I've attended the same events as you and have not noticed excessive amount of brake pad wear. My car is roughly 500lbs lighter and I would say I am pretty hard on the brakes, especially going into turn 1. I run the Hawk DTC-60s (ordered the DTC-30s but due to quality control issues at the plant was sent DTC-60s) and cheapo blank rotors I got off RockAuto. I swap front pads and rotors at every event as the DTC-60s do not have much bite until they are warmed up and the guys at Hawk recommended having dedicated rotors so I didn't have to keep bedding in the DTC-60s.
My daily and autocross pads are Hawk HPS but I don't think they would last very long on track, not to mention the performance wouldn't be anywhere near that of the DTC-60s. Dedicated track pads do have a higher cost but I think it's worth it for the performance. You can order them from Speed Factor Racing, if you want something local, or online. I believe I picked mine up from Teknotik along with some ATE Type 200 brake fluid.
If you are looking to upgrade your pads to something more performance oriented, you can look at the above graph and find what pad/temperatures work best for your application. If you want a pad that is a good dual purpose pad that can be used on the street and the track you can look at pads such as the HP+, Blues, or DTC-30s. They may produce more noise and dust than your average pad however.