When the race office is not available anymore, delivering the protest to the organizing authority meets the requirements of rule 63.1.

Rule 75.1; Entering a Race
World Sailing Regulation 19; Eligibility

In sailing events that do require World Sailing Eligibility, a competitor from a country which does not have a member national authority may only compete if the Board has waived the requirements listed in regulations 19.4(a) and 19.4(b).

Q&A 2020-008

While racing but before starting, a boat shall not touch a starting mark. From the moment the boat starts, the starting mark begins the leg of the course on which she is sailing and she shall not touch it. While the boat is sailing on the last leg and until she finishes, the finishing mark ends the leg from the previous mark to the finish and she shall not touch it.

Rule  18.4 will apply at the finish line provided that the inside overlapped right-of-way boat must gybe to sail her proper course.