The odds seem long, but they also seemed that way for many guerrilla warriors throughout history that took on superpowers. They ran into Galactica...whose to say they wouldn't have run into others.
Guerrilla warriors who took on Superpowers without another superpower backing them up pretty much all have one thing in common. They lost.
What you seem to be missing is that the Cylons could have beaten her through the simple expedience of applying the Zap Brannigan school of warfare. That is to say, they could have just thrown baseships at her until she ran out of bullets.
Logistics matter. Your guns and bombs and fighters and soldiers have to come from somewhere. The Cylons had factories and they were immortal clones. They essentially have an arbitrarily large population base and arbitrarily large manufacturing capability to go with it. You can't guerrilla that, not without outside support.