I should have been more specific, or understood the question more generally as "can you actually negotiate with the hospital on your bills?"

You can do this, even as a living person. I once got a $10k bill reduced to $700. (It took a lot of back-and-forth, but it was worth it.)

We're about to find out too. Dad passed 8 months ago; we got a $1500 hospital bill last week (just after the probate window closed) w/o explanation or description of services rendered.

That sounds to me like the hospital screwed up and is asking for charity. If the probate window is closed before they sent the bill (check the postmark date), then I don't think you owe them anything.