DIY 12 v swamp cooler?

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i live in the southwestern us and 8 months of the year relative humidity is 30% or lower.
i am searching for an ac unit i could set up in the bed of my 1927 Chevy pickup ratrod
and vent into the cab through a hole cut into the rear wall of the cab.
since this is a hand built car and i get to do ANYTHING i want to it.
this sounds like a good idea.
it gets mindbendingly hot around here in the summer and i want to be able to drive my toy.

a gravity feed drip onto a filter with a fan blowing cooled air into the cab sounds like something even I could fab up.
the smaller the better.
i wonder if a cowl of some kind around the exhaust fan would help with efficiency?
i am thinking an old beer cooler with a water reservoir (drip feed) onto a filter of some sort and air forced through it

what do my smartest pals here think?

p.s.
it is so freakin dry around here that rust is the least of my worries.