I agree, EH. Put the problem to bed as soon as possible and don't look for blanket solutions.
I don't see why it would be an issue to explain to the owners that you are putting it into storage at your own cost so that you can move a bed in - but it would be important to ensure that it is adequately protected, you insure it, and that you pay for it to be moved back in when you eventually move out. You can explain that you have back problems and consequently this BZ is causing you difficulty. If they are really friends, it shouldn't be a proble,.