They sound similar to featherbeds of long ago only with a different stuffing. I use to love to lay on a featherbed and depending on the depth of the bed would take it from one room to another to lay down to read a book or just pet the dogs too. We didn't have a tv at my sister's house back in the day. She would get pretty mad when I would pull one off a bed and move it around too.
Your throwbeds sound like fun and may resolve the issue for your sofa, Just know they will be moved from one room to another a lot! It also give me a idea that would be fun for making one.