What possible relevance could membership of an association have to a handicap? That is really bizarre thinking.
Sorry, but your Mozzie is accepted as an F16 under the F16 rules Darryn - whether or not you put a spinnaker up. Does that mean you have to sail on 71.5? Of course not. The same goes for many other classes that would fit within the F16 box rule.
What it means is you can join the F16s, race against them at their events and take home the trophy if you win. Three Mosquitos had a ball racing at the F16 VIC states at Portland earlier this year. Sure we didn't win, we didn't expect to, that wasn't the point of going. The point was to enjoy the race - which we did.