A539, used widely in stock hatch series (control tyre) and is far cheaper than A048R- if you can consistently do 'hot laps' to get the heat into a cut slick, and maintain that level then it's fine, but soon as they cool you've dropped below road tyre grip.
A539 would also mean you're not wearing it out on the road driving to shows etc, they're cheaper too, and I'm not sure you'd notice the half a second or so the A048Rs give you on a track day? Possibly have a set for track day, set for road?