Most of us just leave the existing converter in place but disconnected.
Why?
1. back up charger
2. wire size to a 3000 watt inverter/charger is going to be huge, compared to the oem converter.
3. location needs to be as close to the battery bank as possible, without being in the same compartment.
I chose to use plugs so I can bypass the inverter/charger if need be.
Why?
Because some GFI outlets "hate" the inverter charger and trip more or less instantly.
Regards, Don
My ride is a 28 foot Class C, 256 watts solar, 556 amp-hours of Telcom jars, 3000 watt Magnum hybrid inverter, Sola Basic Autoformer, Microair Easy Start.