oh wow, this looks amazing! I'd never heard of this contraption before but it seems like exactly what I need... I was told once by a physio that AFAB people tend to prefer to/"should" sleep with a pillow between their knees because if your hips are enough wider than your stacked knees, sleeping on your side will inevitably result in twisting your spine at least a little. And I'm glad it works for the cat, too... the real important thing!