It looks like the LED will only turn on when the ACC line is powered, even if the switch is set to 12V. Is this what you want? If you want it to always light, you want that diagonal green line to be a diagonal yellow line coming fron the 12V. But then, it'll stay on if set to ACC and you turn the car off.
The biggest problem I see though: You don't have an OFF position. You either need a DPCO (a DPDT w/ center off) or a 3PDT (and just don't connect anything to the 3rd pole).
I'm sure you're aware that you need to throw two switches if you want to keep the opus and inverter on the same settings. You may want that, but if you don't, you can use a single 3P4T switch instead (they're usually rotary switches though, if that matters.)