Danfoss type refrigerator questions....

Mr Wiz's system goes way back in the past. Panels were being added with time, mismatching is a byatch. Between this and inverter losses of 120V fridge, I would guess some 15-20% of energy is lost.

A lot depends on where you are. I'm shaking my head when snowbirds in desert are complaining that solar can't handle all their loads, so they need to run a genny once a day. No AC in daytime, no freezing temps in the night, hardly any rain, no shade. It can't get any better than that. With LP fridge a 300W flat solar will handle everything in these conditions, and they mostly have LP.

2*6V is marginal for long-term solar boondocking, even without compressor fridge. Doable with 400W, on a strict energy diet, and with LP fridge. Weekend stay is different.

675 amp hrs of agm batteries
679 Watts of solar panel
120vac residential compressor fridge

And I will not deliberately be without a generator
Full timers not weekend campers, that generator is essential auxiliary power

I will add that I like the idea of the Dan Foss type DC power variable speed compressor

And will get one someday

I do not run solar but I have about 500 amp hours of battery.

I can, if boondocking, last longer than the "Quite Hours" at the area I stay on just battery.. one Danfoss type Freezer, One RV Absorption Fridge, Assorted devices running off an inverter (TV, Sat Receiver, Computers, DVR's) and more.

Try 9it.. If the sun don't shine fire up the Honda.. but try it, Might want to go 2 pair of GC-2.

Your bank is a small-ish. It will handle 4-6A of Danfoss, but it won't last long.

Roughly, expect to use close to 10 AH per 1 cu.ft. With 8 cf fridge you are looking at 70-80 AH daily. So - Westend is right, without sun you will have 1.5 days before the bank drops to 50%. With all other loads you'll need 100-120 AH, so - closer to 1 day. Roughly. Depends on the ambient.

400W solar, in NY? You'll harvest 130 AH on an average summer day. Not on the "best" day. And you will be using about that much. This is cutting too close. Have to agree with West, adding another 100-200W is desirable. Honda will help you out, but with 600W solar and (preferably) another pair of 6V, generator won't be needed.

Adding another pair of 6V, or (more expensive) replacing your 2*6V with 3*110AH of 12V, will not only extend you stay with "no sun", but it will also give you the benefit of shallow cycle. Bank will be closer to Full at all times, so you won't need too high charging current. Solar works every day, but it doesn't always generate high amps, as you've probably noticed.

You don't have to carry all the batteries in front. If you go AGM, it can be mounted inside if you have to. They are costly, but being able to do without a generator is worth something, IMO.

First question - does anyone with a similar battery/solar set up have experience with a Danfoss type refrigerator?

No, but I do run a 120V fridge and have done the math. I have 235w of solar and 300AH of capacity. The 12v Danfoss will use about 40AH/day (depending on ambient and use). An owner would decide what weather is expected and what additional hotel loads add to the total. At 110AH of available power, you should make three days of limited use or two days of full use without any sun. My bigger poly module makes a bit of power even in low light, YMMV.
My suggestion would be to add two additional 6V's, somewhere close to amidships if you want to never run the genny or worry about power. If you can add another module or two in the future, you will be fully charged at noon, just like 220AH with 200W of panel.

I got a good tip on this Forum once. If you run low on 12V or need A/C, there are inexpensive campgrounds with electric. I boondock 100% but the option of a hookup is always there.