I'll share my experience, hope it's helpful.
I'm setup on 12V and run two roof AC's(w/Micro airs), 1 Magnum 2812 per AC unit on a shared 1200ah 12V bank. I charge from the magnums when on shore power or generator, and use an upgraded Almott 400a alternator when underway.
The system works well with the exception of welding the combiner solenoid between the engine and house banks on occasion. My plan is to wire in a blue sea relay to fix that issue when I have the time.
The larger alternator means we always arrive with the house bank about 85% charged, and since we replaced the oil cooled unit with air cooled, the engine picked up about 5lbs of oil pressure too. It also means we can charge from the engine or the genset as needed in a pinch.
My coach has a massive number of 12V loads and I just didn't want to deal with stepping down to cover them all, so I stayed 12V. Running AC's from the 12V system works, it's just not efficient and runs HOT. You need a very stout battery bank to handle the AC startups or you will have nuisance trips frequently.
So if I was in your Monaco, I think I'd start by replacing the AC units with the new inverter models to cut your surge and overall loads. Gree has eco-cool, Houghton is being rebranded by a number of sellers, Furrion has one too. When my units need replacing, I'll go this route too and it is going to be beneficial for 12v or 48v setups. I'll bet that (3) inverter units will easily cut your consumption by 1/3, if not half, over 24 hours since they don't need to run 100% after things start cooling off. I have no idea how you can run 3 roof tops off of (1) 2812, that seems like a crushing load for a single inverter.
If you decide to go 48V, just add a second alternator and have it wired up with it's own aftermarket regulator (Balmar, Wakespeed, etc) so you have good control over it. It is super common to have multiple alternators on bus chassis setups, so it's well known and you just need to get the right bracketry, pulley and belts to make it happen.
Maybe you even keep a smaller 12V lithium in place for your 12V house loads, and run only the AC's from 48V. I've thought about that approach in the future. You can get a GREAT 12V battery for $1500 and that really simplifies the house side, add a second 48 to 12v charger and you could even top it off from the 48V side if needed.
Just keep an eye on how your levelers are wired up, and make sure the final configuration gives them the amperage they need to operate. No point in getting stuck somewhere because you can get them to retract when it's time to leave.
