$159 for a pure sine wave inverter! You know what is said about things that look too good to be true. Never heard of Motomaster either.
Be very aware of what the inverter is powering & how much available power you have in the battery bank.
If you are going to wire the inverter so that it could power everything you had better remember to turn some circuit breakers off before turning the inverter on otherwise expensive things might happen.
For a start turn the circuit breakers for the water heater & fridge off along with the circuit breaker supplying the microwave.