Does it glow enough? If not (like too much darkness so they fade) I've done okay with some retroreflective tapes when there's nearby light.
We had LOTS of child gates around the house. I'd walk into them constantly without warning tapes.
Stability-wise: I have GITD tapes on portable electronics which go into small cases, and are handled a lot, and the glued tapes don't come off. The tape is multi-layer so it will eventually start peeling on the corners. There's a top clear layer that doesn't matter much, but I assume eventually it will go bad. Try cutting the corners rounded to keep it from peeling maybe.