There's about 50 feet
of wire between my truck's battery and the battery in my Casita
In addition to what wire size was in my truck I added a 10 guage wire to it.
My 7 pin cord is new and has 10 gauge + & - leads, I've replaced the + & - leads from the front of the trailer through the converter to the battery and eliminated the 3M Scotch connectors.
I have a battery meter that shows the battery voltage and the net charge or discharge of the battery.
With the TV connected and running and the refrigerator on 12 volts more current is taken out of the battery then put in.
Running a refrigerator on 12 volts is way too marginal!
Most run their refrigerator on propane
As far as danger goes in my mind a over loaded 12 volt system poses way more dangers than a refrigerator running on propane