trying to build a big kids cave (Winfield by cdh)

ISO
Edit I measured wrong it’s twin sized space not full sized


Does anyone have a fully foam twin size mattress or foam folding twin size mattress? Abig floor cushion?
Possibly a folding foam couch like those toddler couches but for big kids/teens? Or a memory foam “beanbag/ adult dockatot thing. A futon mattress??

trying to fit a strictly 42 inch wide “twin sized” nook under a bunk bed for two big kid toddlers to share a sleeping cave. Thank you