Smart metering is installed and rates vary with the time of day. Some people can afford to not care about that so asking people not to charge their cars might help.
Just absolutely restrict 240V during peak times then.
From the perspective of your electrical meter, there is no difference between running 2 120V appliances on separate busses vs running a single 240V appliance assuming they consume the same overall wattage. So this would be a very difficult thing to enforce.
That’s what a meter with more intelligence is used (and ya, it would need tighter coupling with the panel where 240V circuits are formed).
240V are what run electric stoves. I guess no cooking either. Why don't we just have a functioning grid like civilized society?