In theory that kind of inverter/converter will have a built in ATS, You should be able to feed it, likely with 10ga wire and a 30 amp breaker, off the main panel and it should pass through. HOWEVER...
The inverter I have is somewhat like yours.. It has three switches that control it.. (And I can add one more if I wish) on the inverter is a switch, if this switch is OFF, nothing works, Not the inverter, not the charger module and no power passes through. NOTHING.
Then there are switches on the remote they enable or disable the inverter and converter sections.. In addition if shore power is present and the INVERTER is "Enabled" then it goes into "Standby" mode.. automatically, and power is passed. If it is disabled, power is passed.
But if the switch on the inverter itself is off (Or if I add the optional REMOTE and turn it off) Nothing is passed. NO current flows.