I leave mine closed except if we dont use it for awhile. In that case i open it to air out and uncrease the fabric. After 20+ years in the inflatable boat/liferaft business, you see the damage done when boats and rafts remain folded for months/years at a time. Hard creases will eventually cause a failure in the coating at the crease. especially where the crease comes to a point. This is more common as the fabric ages and becomes less pliable. Keeping the fabric clean and applying 303 at least once a season is a good way to prolong the life of the fabric. P.S. Never use conditioners that have petroleum distillates in them.
Based on this I think I will change my default to roof up for long indoor storage periods, and minimize the number of times i leave the camper on the truck with the top down for a few months between trips. Probably my camper should be inside on the dolly with the roof up more than I’ve been doing that.
Thanks for sharing your knowledge and experience with the fabric.