The right tool for the job there is really a Smart UPS 3k but they are 30 amp twist lock plugs and really should be on a dedicated ground/ dedicated circuit.
Is there any way you can distribute this load across two or three different breakers? You are pulling a TON of wattage through one spot there.
I'm Canadian and we have slightly different electrical codes.. and to add to that question, can you put in a new, dedicated pair of breakers/lines for the miners? That much power is usually best set as a separate set of breakers. I have had issues where putting a piece of toast in caused the breaker to go until I moved my mining equipment in spite of them suposedly being on different circuits.
Rule of thumb for wiring, breaker to 12 boxes/splits ( 2 splits in 1 box counts as 2 splits ) or total expected amp use, which ever is less per breaker.
Option 2: high amp batteries with dedicated trickle charger connected to an inverter off of the batteries to the mining rigs.