I think your on the right track. I had a 90 amp AMG with solar 45 watt solar panel for our truck camper. We did not have a refrigerator, but ran hair dryers and on cold mornings ran a 300 watt electric heater off an inverter for about 10 minutes. There were some days we were praying for sun, but never ran the battery all the way down.
Good luck and happy camping, Tom