[hbens]

So I installed Pioneer Mini Splits. My SCS units bit the dust. I opted for YN020GMF122M2E a 20kBTU outdoor unit and 2 12kBTU concealed duct models.    
I installed the two concealed duct units inside the current air return plenum. I wanted to make sure I had two separate cooling zones just like the original AC setup. I also wanted to keep the Aquahot for a second method of heat.     
I reused the duct to the rear of the coach      and 4" round insulated duct from Lowe's for the front. I also reused the thermostat wiring so I didn't have to pull new wires.
Each cassette has a manual thermostat I mounted in the curb side bay inline with the new thermostat inside the coach. I mounted the new indoor thermostats above the old ones.
I used 1" duct board from Lowe's to make ducts and close in the cassettes. I used a 30AMP lighted switch to control power at the outdoor unit     and the OEM circuit breakers in the panel in the wardrobe. In the curb side basement I wired up two outlets with the wires from that SCS unit.
The units came right on and blew good and cold. The issue I have is getting heat out of the basement when running the AC. We camped out one weekend in the Florida sun and the unit would not keep up with the heat. While stopped I kept the streetside door open which helped but wasn't enough. On the way home there wasn't enough airflow to remove the heat from the outside unit.
I added an electric fan to suck air out of the streetside basement door.      I controlled this fan with a switch mounted on the wall in the bay. I added a 120vac triggered relay to control the fan from the breaker box inside the coach. This way I wouldn't have to go outside to shut the fan off if I turned the AC off.
This fan wasn't enough so I installed another fan on the curb side to draw air in through that basement door. Both fans are controlled in the bay with different switches and the common 120vac triggered relay. Also, the curbside basement floor vent hole for the SCS unit is covered up now. The streetside basement floor vent for the SCS unit was covered with a grate and I use that to drain the condensation.
After a few hot days in the 90s I realized this wasn't performing well enough. I added two more 4" ducts to the front cassette, through a 4" to 2 1/2" Y connectors through the Aquahot vents below the cabinet under the salon window. This helped quite a bit. I reconfigured the duct for the bottom cassette and you can see the results here.     
I think I need to add additional duct from the rear cassette to help that work more efficiently. Doubling the front cassette ducts seemed to help that run better and improve cooling.
I shot my infrared thermometer in various places in the coach and I am shocked at the temps I found. The windows on the sun side are 110* on the outside and 98* with the shade down on the inside. The side of the coach was 130* below the passenger window, 125* on the black window cover on the outside. Inside it was 84* behind the roll up blind and the windshield curtain. I am looking at making body window covers for the rest of the coach to block the sun from coming in and boiling the inside.
Rubber freon lines are now available. They weren't when I ordered my units. I would definitely pay to use them instead of the copper lines.
This is a work in progress so there will be some changes and improvements in the future.
Thank you Richard for putting your eyes on my project, thoughts and ideas. And for outing me too...
Thanks to the others who have posted their mini split installs and those who responded to them. 

https://drive.google.com/drive/folders/1...sp=sharing Here is a link to the folder of photos I've taken so far.