I like looking back and seeing some progress. And I like your slow swings where you are working on flattening the plane. Very similar to what I need to work on. I struggle consistently swinging slow because <90% is a tough concept for me.
I put up side curtains (like seen on The Net Return). Photo coming soon. not that anybody really gives a hoot. Then I am considering adding an angled top providing it not becoming too "top heavy". I am guessing 18 inches would be okay though.
One might argue that out of doors, the side curtains are not necessary. However, even with the best of players, mishaps happen and it only takes one to break a window.
I can see where the cup faced drivers might be susceptical to being damaged, but not irons. I would side with @WUTiger in regards to possibly the hitting surface being the culprit. For decades people have been hitting range balls with persimmon with no undue ill effects, but I suppose we could consider that the covers were not as hard back then and thus a little pliable. In any event, if it were me, I would exercise on the side of caution.
or......start going to higher class driving ranges that use better balls. (yah, I know,not necessarily feasible).
For me, if I'm finding my course shots going right or if the slice comes back then I will set up on the right side of the range just to mentally (if not physically) give me a barrier on the right to stay away from. Otherwise like someone above mentioned, range time is often exercise and stretching with a little focused practice mixed in during a lunch break on work days.
Matsuyama is my choice this year. He's been so hot this year in tee to green SG. His putting though is worrisome. I'd like to see Jordan in it again but I think the pressure and nightmares of yesteryear will get to him a little. You can never count DJ out. DJ has been really hot with his drives and that can give you a huge advantage at Augusta and his putting has gotten so much better over the last year and a half. Fowler is hot this week, but he's always been a hot/cold golfer, so we'll see. McIlroy just hasn't shown us anything really special recently, so I can't see him contending. If Day is healthy and playing to his former glory, he can definitely put on a show, but I don't think he's in top shape yet. TW is either not playing or will WD.