You can store conforters and pillows for two in the storage box and place it under the sofa-bed.
Me interesa el beddinge.
I bought the Beddinge one year ago and got a faulty metal frame. Unfortunately I only noticed it once the mattress was broken in. It does its job as a sofa, but when I click it down into "bed mode", it's slanted in the middle. I always wake up in the gap in the morning and very often have heavy migraines and neck pain. There's a good Youtube video that shows how to straighten the frame by replacing the screws which I followed, but it didn't help much. Ikea falsly advertizes the Beddinge as an everynight sofa bed. I'm now going to buy a real bed in the next days: proper frame, slats and mattress. Not from Ikea.