Fitted sofa bed cover?

Thanks. They don't do custom fit (and I wouldn't want to pay for custom fit anyway), but they have a huge selection. Might get some Loveseat cover and cut it shorter on one end (near wall) where nobody can see it. My "kids sofa aka adult loveseat" is more like a car seat, it has no arms, it's all one piece that folds and unfolds in the center. 53" long.
The sidewall in front is to cover an unsightly metal framework on the sides and underneath, so I can't put a usual "box cover" all around. Will see.