I’m not a fan of using aversive methods to keep the dog in range, it’s important that she feels good about ranging out and finding birds. The better approach is to use her desire to find birds to adjust herrange. If she tends to punch out beyond where you’re comfortable taking a shot, the next time don’t plant any birds and when she’s not looking, roll in a clip wing bird close to you. Call her in and let her find it. She’ll learn to hunt where she finds birds. Success breeds success. Don't let her see you roll the birds in or it won’t be long before she’s a boot polisher. It’s all about balance. Plant birds out at the edges of your beat to get her to hunt wide, plant them out in the field to get her to range out, etc.
Most retriever owners don’t really teach their dogs to “hunt” upland, instead they let the dog run around in close proximity to them and hope they bump some birds in the air. Over time, if the dog happens to get enough bird contact, he will learn how to use the wind efficiently to bring scent to his nose. If not, he’ll at least improve the hunters odds of finding anything he shoots.
If you want to understand how a flushing dog works, study the Springer spaniel game. There is a lot more to it than just keeping the dog w/in 15 yds or so. A true flushing dog will run a completely different pattern depending upon the strength and direction of the wind. In a downwind (wind at your back) a dog who stays w/in 20 yds of you won’t find any birds you wouldn’t have found w/out him. Instead, he should punch out and hunt back toward you, flushing everything between. His initial cast may be out 45-50 yds or so.
In a cross wind, the dog should run a “banana” pattern, punching out on the downwind side of the beat and angling back across your path. Only in a headwind (wind in your face) should you expect the dog to be running the classic “windshield wiper” pattern of 20 yds left and right. How much ground he takes in each cast depends upon the strength of the wind and scenting conditions that day. Good conditions, he’ll take a bigger bite and you should go w/ him. Once he’s covered the ground w/ his nose, it’s a waste of energy to make him cover it again.
If you're really luck, you can find a spaniel club who will let you train w/ them. My golden goes almost every weekend and he's as good as any Springer I've ever shot over.