As for changing crew, sail config etc. Its simple, you enter a regatta in one setup and you remain in that for the duration. If you want to do it any other way then go sail 12,14,16,18ft skiffs, they love changing sails, masts, crew whatever!

Now i'm not suggesting that this serious approach is needed at a club race but I think you need to be more seroius when you are at a regatta that has outcomes such as qualification for something else or a ranking series.