Do like they do in the late model Suburbans, they have 2 units in them, one in the front, one in the rear and using just one AC compressor with fan controls for each unit. The unit's in the rear aren't very big & the evaporators aren't much bigger then 6x6x12 is size. The set up in my 84 Burb would freeze you out w/both units in use.
The unit looked like THIS with a cover that looked like THIS...Joe