There was some back and forth on this amongst various parties, fueled by the desire of some LRRS racers to run in the Big Fish Little Pond Classic.

I got this clarification from Bob Coy last night:

Kawasaki EX500's ONLY, running in the July 3rd endurance race ONLY, will be exempt from having belly pans as a one time deal to give LRRS racers a taste of the USCRA. In addition, your LRRS license will be honored for this event. (FIM and CMA licenses will also be honored) However, since this is an AMA sanctioned event, you must be a current member of the AMA in order to race. So to make it crystal clear, if the bike is not.a Kawasaki EX500, or if you plan to enter it in the Formula EX class or any other sprint race other than the endurance race, a belly pan must be installed.

Belly pans will be required for the June 15th and Sept. 7th events.