12 volt only refrigerator

Depends on a lot of factors. Will you have electric hookups? If so, it's a non issue. If you won't have electric hookups, the fridge is going to rely on the batteries with no way to re-charge them (unless you have a generator or solar (more on that below)). Then it becomes a math problem. You need to understand the amp draw from the fridge (as well as anything else that will be drawing on them, including 110 items that run off an inverter if it's equipped that way). Basically find out your total amp draw for the weekend then compare that to your amp hours your batteries can provide. (there are nuances to this not the least of which is not drawing your batteries too low).  If you have solar, that's good but most RVs only come with enough solar to keep the batteries charged during storage - not really enough to continually replenish a deep draw down daily. Other folks on here are really well versed in calculating amp hours etc, but that's the basics.