@rbsteinm and I were hired in order to develop an open-source tool which purpose is to crawl a specific .onion website. It crawls the forum pages of a forum and retrieves some information to store it in a MongoDB.
In order to use it, you need to be running any Linux distribution, use python3.5, install the required libraries: pip3.5 install -r requirements.txt, install the tor browser and provide to the commandline your tor browser folder. Also, remember to fill out the parameters that you need in the credentials section of the python/crawler.py file (login, etc).
Example: ./python/crawler.py path_to/my_tor_browser/folder