Food for thought gleaned from experienced and also dependable RV techs. A converter will supply 12V DC power to your rig in absence of a battery ... but think of your battery as the muscle of your 12V DC power and the converter as what is mainly manufactured to keep that muscle at it's peak. Other than using the converter minus a battery for light loads ... using it for heavy loads as in slide or level-up operation just shortens its lifespan over time. Will a converter without a battery run the slides ... yes, but why make it squeal like a pig? Some say that carting the battery in and out of the RV is hard say at the storage lot ... I think that's where a hearty bowl of "Wheaties" comes in to play.
As for a true battery disconnect in place of the OEM disconnect ... lots of us have put a manual disconnect on the negative terminal of the house batteries whether it be a pricey marine disconnect or simply a battery terminal that has a thumb screw to separate the two halves.