J/30 Class Association Forums J/30 Forum The Boat, Sails and Equipment PHRF Racers: Code 6 Mainsail or "Please pass me the roach"

Class rules state in the preface:
Notice to Owners and Sailmakers
It is impossible to foresee every conceivable innovation which may be thought of in the future and to mention every suggestion that has been ruled illegal in the past. When considering anything in connection with the boat or sails or equipment which is not within established practice in the J/30 Class or is not clearly covered by the plans or specifications, you must assume that it is illegal, and must obtain a ruling from the Chief Measurer before attempting it.

Go to the J/30 Class Rules and read section 1 and the subparagraphs there.

I can't see a permanent modification on the hull to accommodate a sprit meeting the OD rules. A bolt-on that could be removed for OD racing would.