I gave up on shaving any hair below my neck closer than what I can do with a beard trimmer. I could never stop the hairs from getting ingrown. I tried exfoliant scrubs, tea tree oil, everything. I'd eventually have to use a sewing needle to pull the new hairs out from under the surface of the skin one by one. It sucked, a lot, and wasn't worth it.
I have very coarse hair and fair, lily-white Irish skin, which are not a good combination, I'm afraid. Anyway, hope you find a solution, because I never did.
Then again, once I stopped shaving and stuck to occasional trimming, I found I was happier anyway. Much less work, and most guys seem to prefer the body hair anyway.