Sorry this is late, I got called out to work on hurricane Florence up in NC.
Here's the update and repair that was done on my camper.
First thing you should check is that the insullation in your slide is good. Mine was missing on the ceiling on half of the slide which was letting a lot of heat into the midbunk room.
I removed the panel (flat section) from the loft area and room area just inside the door on the left. This wall is curved on the outside by the kitchen but has about five inches of space.
Curved section of wall with ceiling duct, loft area flat panel removed, room area down stairs with panel removed.
I drilled a 4 1/4" hole in the ceiling and in the floor area inside the wall between the bunk room and the loft area.
Then I removed the ceiling vent register in the kitchen area just in front of the curved wall to install the duct extension.
Pics of it folded to slide in and folded to tape when inside the duct.
I bought some corplas, (basically plastic material that is used for signs and looks like cardboard.) I made two pieces about 20" long and folded them up as pictured ( this is so that they will slip inside the vent where the register was pulled and you unfold it. (all of the lines in the pic are where the plastic was cut (not all the way through) so that it could be folded.) When you slip it in, it will fit inside the vent and you are able to tape the top half first and then slide it down while taping and then tape the bottom half. I used aluminum tape. (its a tight fit. you will also need to push the tape out at then end of the vent in the ceiling when you install this.) BE PATIENT, IT WILL FIT.
When you get it all in place, you will slide it down to reach the end and tape up the end, I put plastic on the end of mine and taped the plastic in place, then slide the whole assembly down over some of the framing until it covers the four and a quarter inch hole you drilled in the ceiling.
When the hole is covered and centered on the duct, tape the duct with the aluminum tape from inside so that it is sealed and won't move. Use a utility knife to cut a round hole in the plastic through the four and a quarter inch hole you cut in the ceiling inside the wall. I picked up an aluminum dryer vent metal duct and hose. The round aluminum metal is installed up through the hole in the ceiling into the new vent. I cut small tabs on the metal tube to fold over into the new plastic vent and taped the whole assembly from the inside with you guessed it, the aluminum tape.
Optional:
I installed the 4" duct fan motor, use the 100 cfm fan, ( not the 85 cfm fan) and you can get power to switch it from the vacuum cleaner outlet at the bottom, pull the vacuum and ad a switch to the wall when you put it back together to turn the fan on and off, when the days get extra warm. It will work with out the fan running but the fan will boost the cooling when needed.
The factory is now putting this in the newer units ( what I've been told)
I hope this helps.
