This is why I don't think it's practical unless you have a decent headwind. On a calm day, gliders launched at 45 deg's will still level out a bit till the wings take lift. I would think you'd still need to be back at least 50 feet so the shorter length would not pull the plane toward the stake.
I started flying RC with high start gliders about 1970. We flew on the front lawn of JoCo. Comm.College at the corner of 95th and Quivira until they expanded parking lots with those tall light poles. A couple of times, I got a spinning worm burner launch that shredded parts along the grass.