I like liquor boxes for books because they have heavy duty bottoms. And the liquor store might just give them out if you ask.

I might have a similar situation coming up, but I think what I'm going to do is essentially just get rid of most of my books and then try to re-acquire them at the other end of the move. Apart from a few specific ones where the physical book itself is important, like a couple of signed copies I have and some well-worn ones that I've had forever.

I'm also working on cataloging everything in BookWyrm so I can keep track of what needs replacing. Bit of a pain but I just don't think I can physically transport that many books.

I mist admit, I cheated during my moves: I temporarily stored my books by friends and family and slowly moved them over. On the big move I only moved one or two boxes of them.