There are people who have removed the dinettes and may sell you theirs. Another option is a gaucho sleeper couch or a shorter L lounge with retention of one recliner perhaps. All of that is custom.
Try requesting one in the classifieds. The other source is of course Airstream or the outsource company that makes their furniture.
2015 Ford F-150 3.5 Ecobeast 3.55 Lariat