I have been using rolls of painter’s tape to support material that hangs outside the machine when doing passthrough prints, but finally made these instead. This is the same design as the X-Risers posted by @geek2nurse, but are 2.375" high and 5" wide. Super simple, but it’ll save time measuring and drawing them up. I printed 6 sets on Medium (1/8") Draftboard) for 60" board, which gave good support for a 20" width.
pair (shares a cutline):
single (to squeeze in on scrap):