So I am building a 30a PID controller but wanted to future proof my set up so I went and got a 60A Spa Panel. Do I need a small subpanel that uses the 60a wire (after the GFCI) to "mains" to set up two separate 30A circuits if the plan is to start with one controller and move to a second eventually? Would the gfci still protect the entire sub? The plan is to have the ability to run simultaneous 5500w elements but I don't plan on adding the second controller right away. Ultimately I'm planning and eHERMS but starting with a recirculated BIAB set up.