When i was painting, and before I learned that it was the paint job that most people judged (not the actual metal work), I had various handles and loops that would thread into the frame. BB cups with long bolts sticking out, gear hanger bolts with a eyes welded on, wedge expanding post with an eye welded on, rack or fender eyelet bolts with loops welded on. My favorite was the gear hanger loop. It was dimensioned so the loop's eye was centered between the rear drop outs. The frame hung straight down and there was a lot of clearance for the hanging wire to not touch the frame while moving it around during the painting. At one time i envisioned a bar that would go through the head tube with "O" rings keeping centered and from sliding around. At both ends would be an eye to attach a wire. Before I would remove any of the aids I would cut the paint as to not have a chip develop at the border.