I think this is a fine start. I might add a couple of thoughts:

If the owner wants the book back, it can be so stated in that books thread and the book withdrawn.

If the book is somehow lost, it is lost. The exchange parties will do their best to trace it, but it is lost. Owner takes this risk.

Recommend/request/require tracking be purchased at each transfer of the book to allow best efforts for recovery of a missing book.

Shipping out of the US/Canada .......??????

Treat the books well, if you damage it please so state in the thread....owners again accept this risk.

Package it well for shipping, especially at book rate. This means padded corners, stuffed box, to prevent shipping damage. Brown paper around the book is NOT considered good packaging.

This will be fun.