I've got two parts to this for you--advice on product, and advice on wiring.
Advice--
I've had a couple Xantrex products, Prosine 1800 and a Prosine 2.0. I would advise against them only because of service. They don't carry a spare parts inventory very long, meaning, you could have something go amiss in a few years and they won't be able to fix it. In my case, the Prosine 2.0's were becoming known for bad control panels. I called, they didn't stock them any more--it was only 3 years old. I was basically told find one on Ebay or toss into the trash a $1000 inverter. That is not acceptable for any product costing that much. I now have a Magnum Technologies Inverter/Charger, MADE IN THE USA, right here in Everett WA. I've talked to the guys personally at RV shows, they're great.
Wiring--
It's actually a LOT simpler than the diagram you posted. Do you have an onboard gen?
* You simply disconnect the incoming pigtail to the 110v panel (After then gen xfer switch if you have one--you want the gen to trigger the charger to charge)
* Route it to go to the inverter input, then the inverter output goes to the 110v panel mains.
* Connect batteries as instructed.
* Disconnect/remove the existing 12v charger converter permanently.
Done.