Without using the Futaba MSA-10 Servo Synchronizer, you cannot do what you want to do if you use a 7C transmitter. There just aren't enough channels. Also, if you use a pmix to mix two channels for the elevators, you won't have trim on the second channel. If you have a 7C FASST transmitter, then you will have the 'Ailevator' function, which will mix two channels for elevators and have the trim work. However, you still won't have enough channels/mixes available to have two servos per aileron, and separate channels controlling the ailerons.

Basically, you need "more" transmitter. To do everything you want to do with each servo on its own channel, and properly-mixed, then you'll need a 12FG, 12Z, or 14MZ transmitter.