I don't know how big of an inverter you are going to run, but consider the power requirements for an inverter is going to be determined more by the maximum load you are going to apply to it than its rating.
For example, I run a 15 amp breaker on the 120 volt side of my inverter, meaning that the breaker will only supply 1,800 watts.
If I take this 1800 watts and add 20% for inverter overhead (360), I have a draw of 2160 watts on the 12 volt
side, or a max of about 180 amps @ 12 V DC.
Even though my inverter is capable of producing more power than I have it limited to by circuit breaker, I do not need to wire it with the heavy cabling it calls for that assumes maximum output.
I do not have a microwave, and I do not run my air conditioner on inverter, but with this in mind, I have never tripped the 15 amp breaker in normal use. (My whole trailer can and often does run off of this inverter)