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That's right - no need to upgrade your wiring. Just be aware that the function of the "Battery Disconnect" switch will change: Now when you disconnect, no 12V appliances will work whether you're connected to shore power or not. Also, when connected to shore power, the battery will charge regardless of the Battery Disconnect setting.
I agree with @Denny16, if you have the 2x6V AGM golf-cart batteries installed, I'd go for the 60Amp converter as the batteries can certainly take it, and charging will be faster.