If you are looking for the smallest pylon racer and not necessarily a "class" consider the Tiny Toni. It was published in the AMA Model Aviation Magazine. You can print out the full size plans on legal size paper. The weight with a 500 mah 3S lipo battery can be kept under 250 grams (mine was 238 grams), so no remote ID module or registration is required. I radars at 68 mph. Check it out at:
https://www.modelaviation.com/tiny-toni