Big inverter, big cables
It's best to mount a large inverter close to the battery, so there's less voltage drop in the wiring. Otherwise, you need to use very large gauge cables, which can be quite pricey. Also, keep in mind inverters need air flow for cooling. But keep your little inverter, since they are fine for small loads (chargers, TV, etc.) and usually more efficient. I leave my 375 watt Victron inverter on all the time since it only needs 4 watts to run with no load. A second Victron 1200 watt inverter requires more than twice the standby power, so it's only turned on when the microwave is used.