Hi David
Have you tried different layouts of the seat bases and backs? We lay crossways. We have ours upside down, with the two bases parallel in the direction that we lay in (so that you don't lay across any joins), and the two seat backs crossways at our feet. You can also try it with one seat back at your feet and one at your head end to act as a pillow. We find this works well and got rid of the back ache that I was getting.