We had a mattress factory cut a piece of high density mattress foam for the back (bed) of our side dinette 16 ft
scamp and also a piece to fit the side dinette when made as a bed. We also had a duplicate piece made for the side. Used it once and
sold camper. But it worked great. Paid $375 will sell for $185. We are located in SW Missouri.
Bed section will work for any
Scamp - not sure about
Casita.
Shipping probably would not be possible but could meet part way.
Pics on request