ZAMP is expensive ...
The 10 gauge cable (to the wall of you RV) is good for ~ 30A, depending on your panels that can support anything from a 12V 240W to more. The 8 gauge cable has lower loses for the same distance, but is good for ~ 40A, again at least 480W of 12V panels. (see
Cerrowire Resources - Ampacity Charts for reference).
What you really have to know are the specific types of panels that you have (voltage and current), what your charge controller(s) support, and battery bank. With that you can get a recommendation for how to set up your panels for the maximum benefit. Look for series and parallel solar panel setup.
From what you have provided (I am guessing here), you have:
1) A 12V battery bank consisting of 2 85Ah batteries in parallel. This gives you 85Ah of usuable power since they are lead acid and you can only use 50% of the storage capacity before you begin to seriously impact the batteries' capacity and longevity. This is not going to be a large enough for real usage.
2) You have a 1200W inverter. That needs 100A to run it, so you could run the inverter at say 1000W (small microwave) for about an hour before your batteries are dead.
3) You have a 120VAC / 12VDC fridge. I think they draw about 40Ah / day (not always running). So you can run your fridge on battery for 2 days, if you don't use your lights
4) Your solar charge controller will charge your batteries at a rate of up to 40A. A 12V battery bank could therefore handle about 550W of solar input (before you waste power). IF you batteries can handle 40A of charging current, you have to look that up. Now it would not be "bad" to have 600W of solar feeding this charge controller since you would not be getting 100% of the rating of the solar panels in the real world.
So ... lots of stuff to talk about. You have to first decide what you want to do, what your goals are. Then people can talk with you about how to get there.
You could also just wire up the solar charge controller, throw on the panel that you already have, and see where that gets you. What have you got to lose?
Cheers