You hit the nail on the head about the rules being the same as A class, I copied the A class rules and modified them to fit F12 in an effort to get my boats built before the kids out grew them, unfortunately my girls got crews and got big before we could tie the rules down but I’m still building one for my young lad. Personally I think if you can’t do what you want within the existing rules you can’t do it. You’re welcome to open up the rules for debate if you want with the people that are building them now but the spirit of the rules is really to encourage kids to take up sailing and keep sailing by keeping the boats low in price, accessible to anyone, keeping older ones competitive with new ones and not to grandfather any that are built to the existing rules.
regards