Just a thought and maybe it has been brought up but would it be ultimately better for the vinyl if you stored the camper 'popped up'?
Assuming you are referring to outdoors you'd get more wind, sun, etc. wear. General input I've read has been down is fine but pop up and air out periodically.
Indoors and popped could likely be good. I don't know if long term popped up would eventually lower the life of the end supports or not.