Questions about an E-150 (93)

If a work van was never supposed to come with AC at all, how would I be able to somehow get long-term AC in this van?
Also, any good place to get information on installing second batteries for powering devices in the van?

Go to a parts store like Pep Boys ask for a price check on an aftermarket A-C unit. It should come with all parts needed. You may need to modify the interior for it to cool properly. They used to make these but I'm not sure at this time.
The dealer also used to be able to install air conditioning.