Have you looked into ways to make money on the internet? Either through source/selling stuff with e-commerce or taking on gigs online?
If you make money via the internet, you'll have a robust framework against geography. It wouldn't matter if you're in a rural town or a metro area, or if you're out of the country. As long as you have access to the internet, you can continue executing on your online gig/business and keep earning that way.
I think if you want opportunities outside the internet, in a rural area, that's close to impossible. That's sort of the whole definition of "rural" - there's not much going on there (and hence very little opportunity to make extra money because the economies there will be much weaker than populated areas).
For the online thing, I've tried a bunch of different ideas - I outline the process, risks, and my results for various online things I've tried here.