Sorry for the bad news but you can’t get by with a smaller inverter for Induction cook tops by cooking on lower heat settings. The induction cookers do not create lower cooking temperatures the same as an electric burner stove. They still require the same rating of power at low as they do at high. They work with pulses of energy and the strength of the draw of power to create the pulse does not vary. The temperature is controlled with fewer pulses per minute on low and more pulses on high. So that means you will need an inverter that can handle what the induction burner is rated for. There are a few induction cooktops being sold that are less than the typical 1,500 watt rating. Take a look on Amazon for them.My research consists of Amazon searches. There are induction cookers which adjust by wattage, but I have not purchased or used.
With my 600 watt inverter I’d imagine that level would best be used for low and slow cooking, during good solar conditions.