If you are stuck on 13" wheels, you are also stuck with a 10" rotor. Like Warren said, there are threads on converting to vented rotors that involve modifying junk yard parts and using an OEM rotor. But I'm not familiar with them since I was not interested in such an approach.
I work on a track car with 13" wheels and could not accept the overheating of a 13" disk rotor. Regardless of pad selection, the disk could not dissipate the heat fast enough causing the brakes to fade and the fluid to boil.
I designed a bolt on 10" x .81" thick flat vented rotor and an adapter to mount it in the stock location. It utilizes the stock caliper with custom designed shims to space the pads to the new .81" width.
Although obviously not a 12" or bigger rotor, the ability to remove heat allows an aggressive Hawk pad to be used with a significant improvement in brake performance.
Rick