Even 26 foot x 26 foot room to modern building standards will not need 12 kW to maintain the temperature, however I can see how it will need that amount of power to heat it up before the dance. It will depend on the supply as to how you can control them, the problem is one needs to consider thermals, and it is unlikely that adjusting how many heaters are on will work very well to adjust the room temperature.
I noted with interest that the new iVector Myson fan assisted heater has a 5 speed fan, which adjusts speed to suit requirements, but how it selects speed I do not know, as clearly if there was just 0.2ºC between speeds, then there would be a whole degree C droop which seems a bit high.
The lower the droop the more switching is required, and I know with commercial heaters the contactors had a very short life when trying to maintain temperature within a small range, and we had to move to semi-conductor type contactors and of course semi-conductor fuses to stop the contactors burning out.
But type of heater matters, the whole idea of the oil filled radiator is the switching can be less frequent and still maintain an output. One does not want to let heaters get cold, as then the thermals stop, unless using a fan of some type.
There are thermostats which have versions for electric heating
The BTH 002 series do one for electric heating rated at 16 amp, I am sure there are others, in the main designed for under floor heating, but often they don't need to use the sensor. The problem arises when replaced with wrong version. But as said it depends on switching rate, the under floor heating mats store even more heat to the oil filled radiators, so the switching is not that frequent.
So room design and heater type will change what control devices will work.
