I've done a bit of searching and have tried the following guides:
http://www.stuffaboutcode.com/2012/05/r ... share.html
https://thepihut.com/blogs/raspberry-pi ... ge-at-boot
https://www.cyberciti.biz/faq/linux-mou ... ows-share/
and haven't had any luck.
What should make this easier is that I've successfully accomplished exactly what I'm aiming to now on an old Pi (2 B) running what I believe is wheezy.
I remember it taking me an entire day of troubleshooting, and I don't believe any of the above guides are the one I followed.
Here's the fstab from the Pi on which remote drive sharing is working wonderfully:
Link if the image doesn't work: https://goo.gl/photos/qQfJunDMWPoKUoCu9