Then turning off the AC breaker that feeds the converter before powering up the inverter would be simplest way a sTfryman said...
I assume your 3 AC sources are isolated so only one can supply the load center at a time... Shore, genny, inverter...
(Shore/genny isolated by existing transfer switch)
How much solar and batteries are you adding to sustain that 3000 Watt inverter?
At 1000W it will be drawing ~80amps from the batteries...
At 2000W over 160A
At 3000W 250A...
If this is what you have:
https://www.amazon.com/Power-Inverte.../dp/B00NZCRFRQ
it also seems to contain a converter/charger. You might just leave the Vegas supplied converter off...
(Depends how you wired this in.)