With the price of kerosene, and the soot it emits, unless you want to use it in a historical museum setting, I'd consider replacing the kerosene heat with electric.
I am using a 150 watt ceramic reptile heating element that fits a standard medium base ceramic light socket. It doesn't emit light, only heat. I looked for a kerosene incubator before I built my cabinet, and had planned out the heating system based on the ceramic element.
The best way to regulate the temp is to use a digital controller with a probe, either a ready to go model sold for reptile heaters, or a do it yourself one that you would wire up underneath or behind in an inconspicuous place.