I don't under stand what you mean about taking the back off . Mine , you remove the cushions and spread the thin end of the mattress on the bottom of the sofa and inflate the mattress.Put enough air so its not soft .I don't know about the flap, we just put it on the sofa bottom.Airs up fast and everyone that sleeps on it likes it better than the old sofa bed or table.We keep ours in the drawer under the sofa instead of carrying it to some other place.
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2005 F-250
2009 Cruiser 29RK
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