Move Evaporative Coolers

[CC in NM]

We have a 1980 Palm Harbor Doublewide. We have two evaporative coolers on the roof. I would like to replace the coolers with side-draft coolers located on a stand on the ground next to the home and connect to the duct work either through the side or roof. Can you give me some information on how to go about this? I don't know if there will be room in the "attic" to run ducting from the side eave into the existing ducting. Will I need to run the new ducting on top of the roof? I would rather not put it on top of the roof. We will be re-roofing with metal roofing when all this is done, so we can cut into the existing roof if we need to. Any information or tips will be appreciated.