Yes I have broken in a 18yearold bittless
I ride bitless everyday. I ride bitless in every situation, including on trails or in working situations (working cows).
I ride with a traditional hackamore (bosal). So, the answer is "yes", you can definitively ride bitless, but at the beginning you and your horse may need the help of an experimented person to help you.
I think it's absolutely possible, I have friends who ride bitless their horses and they're really great like that, they even compete in showjumping bitless.
I ride with a bit because my horse isn't yet ready to go bitless, maybe he will never be because he can't bear the pressure one his nose!
So I think it's totally possible, but you can't go bitless just because you want to ride bitless, you have to make sure that your horse is fine with it, and that it's safe for you so your horse needs to listen to your demands very well (using your legs, seat, voice and less your hands)