I introduced the dreamfeed right around 5 months too, so it can be done. I had to go with the bottle as neither of us could get the knack of doing it with the breast. We started out with pumped milk, but slowly weaned him on to formula and then always had his df as formula.
Quite a few moms just use their breast, some pump and some use formula, the choice is yours and there is no right or wrong way. It sounds as if you are pretty committed to breast milk so stick with that, no need to introduce something foreign that your cute little girl hasn't had yet.
Dropping the dream feed was a breeze for us. One night I risked it and didn't offer it and the little turd slept right through. There are other methods of weaning the df. IF doing bottle you offer less ozs, if bfing you offer for less minutes or also you can move the time of it closer to when they go to sleep eventually it will coincide with their last evening feed. I guess you cross that bridge when the time comes.
If my son woke up at night we would give him a bottle in the first week, but I think he only did it a few times.
I hope this helps.
But I just wanted to also add that if her night sleep is fine, then you maybe shouldn't mess with it, but if you want to implement one, I imagine you have good reason to want to.