There are several threads on furniture replacement that might help you out. Try to do a search. Have you thought about having an upholstery shop install better quality foam? Might save some $$. I had the same issue in our last 5th wheel.
2017 Gemini 23TR Ford chassis w/ power stroke 3.2
DW, Daughter and 2 dogs, Sofie (black lab/boxer) and Phoebe (schnoodle)