We activated it at :37 and defeated it at 1:27 and then we looked for the star for like a minute lollol
My last picture of actually spawning it didn't turn out but this should be fine. I prefer doing it underground so it doesn't ruin the above ground, so you make your T with the bottom piece encased. So the second picture with the bottom piece showing, except put a block there even though it's not really needed. I find it easier cause the wither is contained and you can more easily hit it, even if you still need to use your bow it'll be a much easier shot. I'm kinda disappointed the last picture didn't work, it showed the placement much better.
Yeah I think it can make it a bit easier, but lol... If you hit a ravine, the wither is gonna have some fun haha.