In the end it all comes down to the rest of the fleet accepting this change (a la mid racing). Up till now no F16 fleet had disallowed it when faced with such a situation but I'm not sure if opinions will be the same whe you try this at a really important event like the Global Challenge. At club race level I imagine it will always be allowed. But you always have to put it to the fleet. The only exception here is when you change the setup right before closing time of the official registration. Up to that point you can change at will.

Wouter