Hi Erik,
I have been debating between the Turnigy and Frsky Taranis systems. I now know that on Turnigy, I can do what I want to do by moving things off the control sticks and onto switches on the transmitter. Tom worked on that the other day and posted a video showing it working.
Can you do exactly that on the Taranis? Move cannon fire, machine gun fire, engine start. etc. etc to the switches instead of the control sticks? I just want the control sticks to drive and run turret and gun elevation only.