I built my own portable and my own dual battery setup...

I like the dual battery because it's got a permanent spot in the truck, I don't have to worry about moving or maintaining it. It serves other things in the truck as well like always on outlets and camping lighting.

I like my portable because I can use it anywhere. I've put my fridge in a rental or another persons car. I've using it for other items that have nothing to do with the fridge or 4Runner.

The portable units do take up some space, and they appear to be more fragile than a mounted lead battery. They tend to slosh around on the trail so more thought in securing things down as well.

I have used the portable in combination with my dual battery to extend runtime. This allows the dual battery to charge the portable, which tends to happen as a lower rate as most are using a DC-DC conversion.

For the money, a dual battery generally provides more watt hours per dollar. I find portables to be expensive, so it's worth cobbling together some batteries in a box yourself. Making a DIY solar generator really isn't that hard.

I prefer larger batteries over carrying solar panels. They are bulky and inconvenient to setup. If you run the truck often enough to provide a supplemental charge, you really dont have to worry about panels. I can run for days without solar. I have panels, I just don't use them.

Both are great depending on how you plan to use it.