First I would run bfgminer as you stated above, then once its started type S to display the settings, then type W to write a config file.  This should save it for you so next time all you have to do is just start bfgminer without the -S all afterwards (I could be wrong, never done it that way, but seems like what you would do).

Now, auto starting is the next step. I know this works for Minepeon, but I dont know about Raspbian, but they are similar so why not give it a try.

Try:

sudo systemctl enable bfgminer.service
sudo systemctl start bfgminer.service

Reboot and see if that works.  I