Recovering from Books sync failure

I used to have my Books collection synchronized across devices, so I could continue reading on whatever device was at hand.

Today I found out that, for some reason, my macBook has decided to wipe its entire Books library and then sync that empty library to my iPhone.

Now the only location I still have my old library is on my iPad Air 2, which (thankfully) I haven't synced in months.

When I connect the iPad to the macBook via USB, it starts a backup in preparation for a Sync. Going to Sync settings for Books, "Sync" is enabled. When I choose to disable it, the Mac asks me if I am sure I want to wipe the library on the iPad....

The iPad is not set up for sync over Wifi, which would again require connecting via USB.

I have tried to share the books (one by one if I really have to) from the iPad, but the only thing it "shares" is the book title.

What is the best strategy to recover the library from my iPad?