I curl mine around to form a tube (top part resting on the deck.) No bends, no stress on bottom part, etc. Just seemed the best way to do it and very tidey.
TR7 Spider - 1978 Spifire - 1976 Spitfire - 1988 Tercel 4X4 - Kali on Integra - 1991 Integra
Just unzip all the way round and let it rest on the rear shelf. It's one benefit of not having a glass rear window in a convertable. (I can't think of any others)