Quote Originally Posted by Ronin View Post
my plan (in theory) to skip the whole dual battery setup completely.

I have a cheap AGM deep cycle that was given to me. SO when I am driving I will have the fridge/freezer connected to the rear 12v cig socket that runs off main battery. Once I am at camp site, I will plug it into the spare deep cycle and connect the solar to the battery via a mppt controller.
No problems with that setup at all, it will work fine.

The two main reasons for having dual battery systems are;
1. The second battery is for deep cycle low current use and permanently on board as is the load IE fridge etc all stay with the vehicle
or
2. You need a dual battery for high amp applications on the vehicle IE lots of winching, humungous doof doof sound system, etc

If all you do is chuck a battery in the back when you go camping and the fridge etc all stays at the camp then your idea is fine