New inverter+battery install in greyhawk 31fs

[nottherealfloridaman]

Looking for a bit of advice on installing a new inverter and AGM batteries in my 2013 Greyhawk 31FS.

My coach came with the standard inverter that just powers a single outlet, which is not suitable for situations where I want/need to boondock and can't use my generator, so the overall goals are to upgrade the inverter and batteries to support a few outlets, the fridge and microwave. To make this easy, my intent is to move the circuits I need from the main breaker box to a sub panel. The subpanel will get power from shore/genny when they are on, but from the inverter when on battery power.

After much research, I decided on the Xantrex freedom 2000 watt, primarily b/c it has enough power for my needs and an internal transfer switch, so I can wire it easily downstream from the existing main breaker box to the new sub panel and the auto transfer switch will handle switching between battery power or shore power as needed. I've got 2 brand new 100ah AGM batteries as well, might add more if needed but for now I only plan on needing to get through 1 night without shore power.

So far so good. (I think)

I have 2 issues: 1) The location of the existing inverter is under the bed along with the main breaker and all of the AC/DC connects, the location of the existing battery is at least 10-15 feet away and 2) the cabling Jayco used between those locations is 6 AWG, which seems underspec (the Xantrex says it wants 2/0 AWG between inverter and batteries)

My original idea was to just put the new batteries in a compartment next to where the existing battery is b/c that is where all the battery cables connect and it seemed easy. However, based on my research it seems that the inverter needs to be essentially right next to the batteries, within a few feet, no more than 5 feet.

Given that, I see 2 options:

1) Install the AGM batteries and the inverter in the storage compartment, run romex cabling from that location 10-15 feet up to the main breaker and the new subpanel. (not ideal, but possible)

2) Install the AGM batteries and the inverter in the under the bed compartment. I have room there, all the AC/DC cables I need are there, everything would be within a few feet of each other and I can easily use the recommended AWG cable between the batteries and inverter.

Option 2 seems to be the preferred option unless I'm missing some show stopper issue.

However option 2 does create a complicating factor: what to do about the existing battery and its downstream connects. I could for example just leave the existing house battery in place and its downstream connection to the 12v portion of the panel, this would mean I would use the new AGM batteries ONLY to power the inverter. In order to get charge from the coach alternator to the new AGM batteries, I could install a battery isolator so that it could charge both the current house battery and the new AGM batteries but there would be no connection between them.

The other option would be to re-wire the 12v to the new batteries as well, and install a new battery disconnect near the install of the new batteries, then just bypass/remove the existing house battery and disconnect, so both the 12v and the inverter would be powered by the new batteries.

Would like to hear any comments/thoughts on the above or any advice from folks who have done something similar.