1992 Dodge B350 Van A/C

[popof9]

My A/c works reasonably well, but I’m wondering, when this R-12 A/C system finally does go out, would it make sense to cut a hole in the van roof and install a Coleman camper a/c unit or similar product? The place where the cut would go is already moulded into the roof sheet metal. But I wonder how I would provide for the power draw of the camper a/c unit. Is it just a matter of installing a higher output alternator, or is there more to it than that? Any input appreciated.