On a previous (Heki) model, where the fitted blind did not enjoy being left extended for long periods, I cut a piece of lightproof fabric to the size of the frame, then applied pieces of self-adhesive velcro to the frame on the four sides, with the corresponding velcro attached to the fabric, and used this as a sunblind during storage. Advantage is when you take the fabric down you just fold it up and tuck it away easily for next time.
Current van has (two) Remi sunroofs - clear - with pleated blinds. These I find are OK left across in storage, and I have not suffered any problems to date. Hope this helps. Richard.