The panels are providing about 18 amps between 10 am and about 5 pm. 7 amps otherwise.
This seems low. I was expecting somewhere around 30 amps.
Too Tired to crunch all the numbers sorry but this is one place you are going wrong straight off.
Your 30A would be IF the panels were giving their rated 100W. They won't/ very rarely will ( Bright summer sunshine perfect tilt/ angle maybe)
I ran my fridge for months playing around and had a 24V system and ran 1600W of normal house type used panels, through a cheap but effective PWM controller. Worked fine but a few cloudy days and I was dropping volts fast.
Just note if you use household 30V approx rated panels, you have to run a 24V system because you will fry the controller if you try to input 24 and charge 12 with the cheapie controllers. Ask me how I found out!
2x12V batteries in series for 24 is the same capacity as 2x 12v in parallel anyway. You will need a 24V inverter though.
My theroy I have come up playing with solar is you have to size not for the bright sunny days but the cloudy overcast ones. I inadvertently came up with the same practice as now being done on home solar installs, over size the array to your inverter. I also came up with the theroy that its not the peak sunshine you want to try and get max amps out of, its the morning ramp up and the afternoon wind down. Extra amps here make a big difference to the days' Kwh Yields.
If you have say a 30 amp controller and 100a of panels, the controller will just take the 30 A and discard as it were the rest. You can't go high on volts, but you can go high on amps. By going over on the panels you get more amps in the morning and afternoon and full amps through the day. In cloudy weather you get a lot more amps to help carry you through as well. Other thing I did was run 2 of the cheaper pwm Controllers. This way if it's available, you could put say 60A into the batteries and they will share the charging BUT, check the outputs with a multi meter and set them up that way.
the controlers I had were the same makle and model and were out by 4/10ths of a volt which will make one work harder than the other.
Check with a multi meter and I wrote the - figure on the high one so I knew how much to skew that one to match the other and which one was what.
If you are planning on leaving this running at your cabin then you'd want to massively oversize the battery's and the panels because if the inverter shuts down it will stay that way till you reset it. Least every one I have seen but there maybe something uber expensive that does it by remote control or automatically. Still probably better to invest in more panels and batteries.
The main thing is don't take things at rated value. They rarely work that way. Panels won't produce rated power, controllers may not provide rated charge, batteries need 50% more power in than you get back out, wiring has resistance and so it goes.
As mentioned, Filling your fridge/ freezer ( I used bottled water) is a good idea. Gives thermal mass that will help keep stable temps and the unit cold overnight when it's not being opened and there is no charge power. Take the bottles out as you need to add food but basically the idea is to keep the thing full. Put in the food you need and then fill the empty space to provide a thermal mass. Of course Fill the thing initially in the morning when there is plenty of power to cool it all or add gradually.
