I have a 2008 38. I didn’t do the install, the boat came new with air conditioning installed.
Dometic now owns the business that makes the units so check their site.
as for ducting, I’m not sure but check as Hunter pre wired, pre plumbed for many optional features. Mine came wired for things like TV cable jacks, and wired and plumbed for a high water high capacity emergency bilge pump so take a look as they may have run ducting for air conditioning.
in the aft cabin the unit is located under the berth towards the port side. Just to port of the fuel tank. The air return in just under the bed. The ducts for air go port and starboard and come out in the side of the hanging lockers facing aft. The backs of the hanging lockers come out by screws and there is space behind the panel for the ducts. My aft unit also has a small duct that comes out in the head under the sink.
The forward unit is located under the forward part of the settee by the table. The air return is In the front of the seat. The air ducting goes in a number of directions. The first goes forward to the forward cabin. It comes out above the hanging locker on the starboard side. The back of that locker is easily removed too.
For the main cabin there are two runs. One port and one starboard in the ceiling. There are several openings on each side so you can distribute and direct air throughout the cabin. Starboard side goes back to the galley. Port side back to the nav table.
one more thing. There is one water pump that supples both systems. The pump is located under the floor in the main cabin about mid cabin. It’s mounted high in the bilge. The intake through hull is located in the compartment with all the through hulls at the bottom of the steps. The output of pump is split with one going to the forward unit and discharging through a through hull located on the starboard side above the water line. The other goes aft to the rear unit. It discharges on the starboard side far aft via a through hull located in the stern locker.