Actually, a easy solution for this is to install a simple 120v 18A relay from Amazon with "Normally Closed" contacts. Link to Amazon part is below. Costs less than $8. Got a pre-stripped lamp cord from Walmart for $3.50 and plugged it into the inverter and use it a to energize relay coil. and then switched the black wire on the converter outlet via the relay so that when the inverter is on, converter is off.
It sounds complicated, buts its really very easy and foolproof. You will never have both on at the same time and no manual switching necessary. Buy a cheap j-box and blank cover to protect it. Less than $15 for everything
Amazon Relay
