Yeah, I'd ditch the "tennis pro" thing completely. Maybe give her a profession that would give her the psychological make up to be able to handle the strain of the bionic implants without going mad. Not sure what exactly, but give her a profession where she'll choose to use her bionics to help others rather than hurt them.
I believe you wrote that in the original series, Barney Hiller was a race car driver critically injured in an accident at the track. Then he was chosen to receive bionics and become The 7MDM. He likely became a race car driver because of the adrenaline rush he gets from driving fast (why many drivers elect that particular vocation). So when he discovered just how powerful he was, he became mad with power. Using his bionics to hurt others was an even greater rush to him than racing cars.
It's my theory, as I stated before, that Colonel Austin was able to handle his bionic implants because he was a test pilot. He knew from day one that any time he got into the cockpit of an experimental air/space craft, there was a chance he might not live to see another day. It takes a certain special kind of person to do that without losing their nerve. And it requires the same special sort of someone to receive powerful bionic replacements without going mad. Jaime should have a profession that requires that same sort of nerve. Perhaps her going skydiving wasn't recreational. Maybe it was professional. Maybe she teaches skydiving for a living. Or maybe she's in the military, 51st Airborne Division or something, and was on a training mission, teaching new recruits to be paratroopers. Something like that.
Well in the reunion movie Return of the 6MDM and Bionic Woman, Jaime was now a fully qualified doctor/ psychologist who helps others adjust to their bionics. Also, in real life, Lindsay Wagner seems to be into this sort of area (minus the bionics). I suppose that could work, but that's really more mature Jaime, not young Jaime.
Skydiving teacher could work as you say. In the series, she was understandably scared of ever going skydiving again after her accident (she once took a helicopter to go to a mission destination instead of parachuting out), so making it that it was once her profession and now she's deathly afraid of it would make it all the more poignant. I do like that she has fears (she was also scared of snakes) as it makes her more vulnerable and accessible, and that was part of her charm.
And of course, being a skydiving teacher, she would have transferable skills - ie TEACHING skills, which would lead her to being able to work with the children in the classroom at the Ojai military base, as in the series. Actually, Jaime did say in the first actual Bionic Woman episode "Welcome Home Jaime" that she had a teaching degree before turning tennis pro (if she did, that's a little late to turn tennis pro as most players these days are already in there by age 16 if not younger).
I would say to not actually make her a ranked officer in the military, but just that she worked with the military as a civilian instructor (hence her later connection to the Ojai military base). Part of the charm of the original character was that she wasn't this specially trained operative who was so sure and confident of herself. She had to learn it along the way and still made mistakes. She wasn't this tough military brat who needed to prove herself. She was just "tough" because of her bionics and psychological make up. Having her a fallible and rookie agent makes her more human and would be a breath of fresh air (especially if she has the same personality as the original) in this day and age of tough broads who want to show they're the man's equal.
I suppose if you wanted a slight nod to her tennis background, we could say that she originally wanted to be a pro tennis player but never got very far because she had a career-ending injury early on as a teenager before she ever turned professional and competed (hence why she would be unknown). It wouldn't have been something that incapacitated her, but would just have made it difficult to continue at the top of her game on the tennis circuit, so if she couldn't be at the top she would rather not play at all. Hence she decided to concentrate on something else which gave her a thrill - eg skydiving. Or maybe she initially took it up purely to live on the edge to try to dull the pain of not being able to be a tennis player, but eventually came to love it and then made a (temporary) career out of it.
Maybe if she works at the air force base as a civilian instructor, that's how Steve comes into contact with his childhood sweetheart again. He could ask her what she's doing here and say that he thought she was going to be a tennis player. Then she could tell him what led to her career change. Maybe she'll have to then work with him on a mission leading to her parachuting accident. It could even be, depending on the plot and how everything is written, that maybe Lisa Galloway (who is an agent) was meant to go on that mission with Steve Austin, but was tossed out of it. Then somehow Jaime took her place (not sure how if she's not actually trained but we can figure something out) and Galloway got wind of this and sabotaged her parachute.
You do know though that in the 6MDM episode "The Bionic Woman" in which Jaime debuted, that she wasn't able to handle her bionics and did almost go mad under the strain of those excruciating headaches from her bionic rejection? Then she seemingly died on the operating table but her heart was restarted by Dr Michael Marcetti who then cryogenically froze her so that they could operate on her, but didn't tell Steve. So even if there is some initial rejection, it wouldn't be a bad thing. She would be more able to try to reach out and appeal to someone like Barney Hiller and tell him she knows what he is going through so he doesn't have to be like this. Of course, he would not hear her, but it would give her that sense of trying to restore him even if it is ultimately futile.
