I did something very similar with white vinyl 3 rail fencing. First post came out super easy, the second post was set in concrete and I bent my hay spear getting it out. Then I learned that it's just about impossible to unbend a hay spear. I also learned that a bent hay spear doesn't slide out of a bale very well, so after a year of dealing with a bent spear, I bought a new one.
Lesson learned, I should have had my spear all the way though the post, but I'm not pulling anything out of the ground with my hay spears ever again!!!