Blow up beds in couch

The blow-up bed on my Outback couch is awful! The couch itself (folded out to a bed) is too short and the both ends of the blow up mattress overhang the support. It works OK for two small children (my grand daughters slept on it, and worked great for them). But my wife and I tried it and we both hated it. The support under the mattress is uneven also. Feet end is higher than the head end with a big bump in the middle.

NOW.... when we put the blow up mattress on the floor, it was pretty good! But the couch as a bed .. absolutely stinks. It's great for a couch, but not a bed!