[Latitude 28]

Forest, since Jack took Mary Poppins, then I suppose I'll have to identify as Goldy Locks then.

As a refresher, I replaced two 2ton SCS units with one 24k ducted mrcool, which was bought through a dealer, not as a DIY kit, so I also have a full 10year warranty. I sealed R2 at the under stair return plenum and vented the minisplits outside unit exactly like the SCS, intake air thru the floor near centerline and exhaust is thru the floor curbside in its own fabricated sealed duct. My original concern was air mixing under coach, but I have seen no difference in performance whether or not I separate that air or not.

L2 houses the ducted inside unit, like Jack installed midcoach above his fridge. The floor was sealed with new sheet metal and supplies return air thru entry stairs, again as originally designed. I had ductwork fabricated to connect the ducted minisplit directly to the original Newell ducts that supplies the entire coach. the only thing that I changed was to add one additional 5in hose into the salon. finally a condensate drain is plumbed thru the floor to just dump on the ground.

The one thing I overlooked was winter condensate/defrost drainage in R2, which has since been remedied by installing a fabricated drain pan. 

Would I do things differently if i were to do it again? A tiny tweek here and there, but overall, with 3 1/2 seasons and almost 1 year of use, I am quite simply thrilled. 
Our temperature has ranged from teens to very hummid 100+

Thank you again Jack and Tim for all of your patient help (aka. 40thousand pestering questions) while i was planning out our system.

Arch,
Looks like you had removed the original SCS carpeted central return air plenum....is that correct?