You have the right idea by starting from the very beginning.
This is also a socialization issue. I agree with Steve that by using the Hillmann theories of excitement.
I would also use Hillmann's suggestions from his puppy videos of the handler being the only source of joy in this dog's life. This dog has a distrust of humans, and you will need to earn that trust and respect.
Below is how I would begin before I got into any real 'training' with her, as yard work is NOT what she needs at this point.
Isolate this dog from other people and dogs so that only her handler will feed, air, and play with her.
When you go into her kennel in the morning, tell her to 'sit'. Once she is sitting, stand there looking at her until she makes eye contact. When she makes eye contact with you, IMMEDIATELY say 'good' and give her a treat. (NOTE: I agree with Bill about treats, but you do not want her to watch your hands. Already have a treat in your hand or keep in a pouch behind your back. You want EYE contact first, then say GOOD, and give reward.) Now release her with your release command and let her out to air.
Keep a pocket of treats handy. Use them to reward her when she looks at you and to make her obey commands. Use a key word such as 'good' when she complies.
Now I would take her back to her kennel and get her a bowl of food. Do the same thing and say 'sit'. Open the kennel door and place the food on the ground. Do NOT let her eat it until she looks you in the eye and then say 'good' and release her to eat the food.
Use the same routine each time you open her kennel door. Say 'Sit', wait until she makes eye contact, say 'good', give her a treat and then release her.
For the first few days, I would take her out for short walks. When she makes eye contact give her a treat. You can also place a small bumper in your back pocket on these walks. If she starts making eye contact for longer periods, you can alternate saying 'good' and bringing the bumper out as a special reward. Use it like Hillmann does for excitement, not necessarily the retrieve.
Wave the bumper like a toy to create excitement getting her really pumped up and then make a small toss. Only do this a couple of times each walk and then put her back in the kennel.
Use the same routine each time you feed or get her out of her kennel.
You will be her only source of joy. You will make retrieving a bumper fun for her again, but only after she makes eye contact with YOU. Do you get the idea? Transfer this excitement to the yard. Keep it fun!
Females are funny and do not usually like yard work. You must make it seem like a game and not work for her. You will have to study principles of motivation to gain her trust and get her to work for you.
Good luck in your project!