Another possible option is the hemorrhoid donut spare tire option (I hear it corners well):
Vive Inflatable Tailbone Cushion - Hemorrhoid Pillow Donut for Pregnancy, Piles, Coccyx Pain Relief - Orthopedic Treatment Doughnut Seat - Ring Chair Pad for Prostate, Sciatica - Inflate Assist Valve
https://www.amazon.com/dp/B07146JPWL..._C2bZEb9DST5P9
Serves multiple purposes.