Sorry, no there isn't. If you want to transfer that many books then you should just connect with a wired device...like iTunes *shudder*.
The whole purpose of an OPDS is that you don't HAVE to download all those books to your device - you simply download the few that you want/need
as you need them. If you allow access to your OPDS server through the internet, then you can download any book(s), at any time, from anywhere.
In addition, you can use your Calibre content server/OPDS the way it was intended - as a library manager. You can view your entire library via a web browser - such as that on your phone/tablet - download selected books to your device for reading, or read directly in the browser.
Cheers,