I've seen some movies on youtube of people sneaking up a sleeping dragon and then one-shot kill them.
But is it possible to fight a dragon in the open and do a sneak/backstab attack? How?
I kill almost everything in a single shot with my dual dagger backstab. But since I have little armor, A dragon
can just kill me in 2 fire/ice blows. I'm level 25, still need unrelenting force word 3 and the shadow warrior perk.

I don't play a pure stealth, so I've not one shot a dragon with backstab, but I have managed to sneak up on one. It was night time and it was a dragon guarding a word wall and I just snuck up the mountain to it like I would any other monster in the wild.