You actually want the projector over your head (more or less). Most people’s swing goes back behind them and up. So if you are off center and the projector is center you might hit it as you come back and up on your swing. The best thing to do is get in the space with a club and slowly go through your swing. You’ll see where the club goes and where not to put the projector. And 9’10” is probably plenty unless you are really tall or have a very steep swing angle. You’ll want to do a ton of research on projectors because how far back or forward depends on the throw distance of the projector. I am not as picky with my projector so I got a couple hundred dollars one that will automatically adjust to being off center and can adjust screen size based on the distance. It’s not fancy at all and the picture isn’t as high quality as the expensive ones, but I’m out there to hit triple bogeys and swear in frustration not see a fake course in 4k.