Need help with RPC and 3 phase panel configuration

I am building a new rpc for my shop, and need help with the configuration with the building wiring. I have a brand new WEG TEFC 20hp motor for an idler. I know theory on rpcs and have no trouble wiring residential.

What i'm trying to figure out is the best way to wire it in. I'm going for automatic operation. I have a PLC to operate everything. The idler will be driven by a 2hp air compressor pony motor driven through a Kebco clutch. I will be engaging clutch, spinning up the idler, then declutching and engaging the idler.

The part i'm having trouble with is the building wiring / 3 phase panel stuff.
I have a ton of equipment to support this already.

My thought was Come off the main breaker panel to a Nema 4 contactor, then into the 3 phase panel, and the idler is fed from a breaker in the 3 phase panel into a nema3 motor starter. Somewhere i have to put all the balance caps and i don't know where all that should go.

I wanted the contactor between the main panel and 3 phase panel so i don't have only 2 of the 3 lines energized all the time in the shop so nobody inadvertently tried to fire up a machine.

I've been searching, but it's tough to find something relevant to what i'm trying to do. I am going to keep my compressors 3 phase so i need something that's fully automatic in case a compressor wants to run when i'm not around.

Any thoughts ?

Are you wanting the RPC to be off when machines are not running and start automaticly when a machine starts? Like the air compressor example you give?

Yes, exactly. I don't need the additional wattage cost when it's not needed.