Another suggestion (assuming nobody here knows of a substitute) is to contact UltraRVProducts in Chehalis Washington. They are an iRV2 sponsor and are Workhorse specialists. They used to have a shop in Washington state (Brazels) but have now closed the facility and are only providing online parts and performance products for RVs.
They used to sell Crystal Air kits but no longer see it on their website so I'm guessing it's no longer made.
Somebody there may know of a substitute product if it has been discontinued. I have to believe it's no longer made as I don't see it anywhere when doing a search.
Ultra RV Products
800-417-4559
Curiously, they still have the old installation instruction for the kit on their website:
Installation Instructions - Air Conditioning Kit - Crystal Air - AC1001/1