At my course we have two spots where you can get hit. The first is off the first tee. The main landing zone for those that spray the ball is out of sight of the teebox. So if your entire foursome has botched tee shots, the next group can come up and figure the hole is clear (you can see tee to green).
I've hit into the above scenario. When I'm part of the above scenario, I take two or three
clubs, and leave my bag or cart in the fairway to alert the group behind that we're still within range.
The second is a short par 4 (300 yards). It's a dogleg 90° right, 150 yards to the turn. But after the turn, you go up a steep incline about 30 yards to a blind green. There's an extra tall flagstick, but you can't see it unless you get close to the trees (about another 20 yards back from the 150 marker). The other problem this presents is that if you're going to try and drive the green (only 225 yards as the crow flies), you have no idea if the group ahead is putting out.
A bell would not be a good idea here, as the next tee box is 20 yards from the green.
The solution is one I've seen on another golf course. You hit a downhill tee shot through a small opening through some trees to a landing area. You cannot see golfers in this landing area through the trees. From this landing area you hit over a waste valley to the green. As you approach the landing area, you press a button, and a stoplight in the trees facing the tee box turns red. As you cross the side of the valley, you hit another button (when you're obviously clear), and the light goes green. This is the solution I think would work at my course. A little stoplight in the corner of the dogleg. When it's green, hit up. Once you get up the hill, hit a button, turn the light red. On your way to the next tee box, turn it green again.