How do I remove stuck trailing arm bolt?

I'm trying to replace the rear driver side trailing arm and the bolt seems rusted to the frame and bushing.

I have tried PB Blaster multiple times and it hasn't loosened the bolt. I have tried hammering it out to no avail.
I also tried using a vice to press the bolt through but ended up just bending part of the car frame.

The head of the bolt seems to have some kind of locking mechanism on it, this makes it very hard to keep a socket on it without slipping.

Any help is appreciated. I plan on replacing the rear passenger side as well.