Cant help with the reasoning behind your outside vent install, but I have a 2006 with the gaucho bench located just behind the drivers seat - all my electronics are stored inside that bench cabinet along with my water tank & pump. I do not have any outside venting, and batteries are located underneath the Van. But, I'll attest to the fact it gets very warm under there, more so when plugged into shore power.,,enough heat generated that it concerned me.
I simply installed seven of these across the top of the cabinet front of the gaucho, and two more on the sides. Used a hole saw to drill the holes (1" from the top) and just pushed the plastic vent covers into the holes (fit nice & snug). I already have two larger air vents located on the lower part of that gaucho cabinet, so the air circulates nicely.
Unless someone else can reveal a good reason to have the vent, I'd also plug it (especially in the winter).