Closer to 5 to 1 if we include our NPCs, but that's assuming the wyvern doesn't turn up.
If it does turn up, though, it'll most likely choose to eat the recently dead rather than the living, like any predatory animal. So there's that.
I don't know exactly how you picture it in your head, but a distraction will not empty the camp. Especially if the distraction is intended to warn the goblins that their highly-defensible position is about to come under attack. All it does is waste the element of surprise.which is why I say distraction to empty the camp and stealth.
Stealth will get us nowhere. We may as well be ogres trying to sneak into a human city that's on high alert.
In-character, though, Elsa needs convincing that the two sacrificial victims are worth risking our lives for.