Is it possible to download (not just sync) and entire audiobook to an Apple watch

I have the latest software update on my Apple watch. The same problem remains however. It appears that Apple will permit me to sync an entire audiobook (and the next one on the list if room) with my iPhone, but will permit me to actually download the first five hours of the audiobook. And, after I have listened to those first 5 hours the sync function will not permit additional download of content to the watch, but simply keeps it synced with my iPhone. I have ample room on the watch for several audiobooks. This is frustrating, for my intent is to download the entire audiobook to the watch so that I can use the watch at the gym or riding a bike without having to have my iPhone with me. All that I have been able to find from Apple Support is that the sync is possible, but only the first five hours for download. Am I missing something? Thank you!