In my day, all you could find in the UK were 9ft widths of roll; I used to have a separate set of the vertical poles on which I hung, horizontally, the rolls not being used, and these all had conduit tubing (metal) down the centre; no problems with that. The only solution with white, pre-PS, was to overlight the background and hope you didn´t get enough spill to kill the subject.
Rob C