I always go for a dual battery. I like having the capacity, flexibility, and peace of mind… I do all my own design/electrical work and I like these types of projects so I don’t look at it as a huge cost or hurdle.
That said, over the years of running an efficient fridge like the ARB 50, I know I can get away with a lot less battery for weekend trips.
Portables are also worth considering. So is just adding a small ~50 watt solar panel and a charge controller to the truck to help maintain a single battery setup when sitting.
With a little DIY spirit you can take some small SLA batteries and an ammo can and easily make something that can run the fridge overnight. Add a solar charge controller and you have a budget Yeti
If all you are running is a fridge when the truck is off, you have a lot of options.