I did already email you back, but hadn't read the thread here yet-
if you're gung-ho Navy, not able to be a Nuke, then I would insist on taking the DLAB. It's the test for Crypto-Tech (Interpretive).
It's a great field, they teach you Arabic (well, there's a chance at another language, but with the situation as it is, count on Arabic or perhaps Korean). You 'spin and grin' which involves listening to three or four different frequencies at the same time, try to find out crazy stuff- interpret..
plus there are some really great options for CIA work, NSA work, that kind of thing. Bonuses are about equal, quality of life is seemingly a bit better.
It's not nuclear power, but it is a bit 'geeky', and had I known of the field prior, I probably would have gone for it. Not that I'm not happy with where I ended up, because I am. However, as to cross-rating... that's a tough sell.
If they need medics, they'll never release you. Navy is real tricky to cross-rate.
Good luck, like I said before, I sent your email on to a Nuke recruiter friend of mine, and should hear back from him soon (recruiters work crazy long hours, so 'soon' could be a couple days)