I run dual batteries but the second one is mainly for this
That's a 50lt fridge and will hold about 48 cans of beer and a bottle of wine for my wife
Most guys down here in Aus will run a second battery if they're running a winch but it's more of a safety thing as when you're touring you cant afford to be stuck with no working battery.
have 2nd batt mounted in the right rear corner, I cut the plastic fender trim to put the battery out of the way. I carry a Ready Welder so I have the batts to weld
Oh - and it's "dual battery," not "duel battery." Just for your edification, a "duel" is a fight of honour between two people - kinda like the old "pistols at ten paces" thing. Just so you know - spelling is taken literally by computer systems, and taking the time to check if you're not sure will help those who come after and search...