You Will Have to Travel
The short version of the answer is: you will very likely have to travel, the user base is not very large, especially not those forming the largest strongly connected component of the web of trust (ie., the network of people all being able to mutually find a trust path in the web of trust). Less than 100.000 people (as of 2017) form that group, don't expect many of those living by chance near you "in the middle of nowhere".
When looking for certifications on your OpenPGP key, also consider what community of people you want to be trusted in. Just having "some certificates from trusted people" does not really help you at being trusted by all OpenPGP users, not even those being well connected. If you want to get a trusted identity in a given group, especially try to meet with people from that group. For example, meet Debian fellows for signing keys if Debian is (one of the) groups you want to participate and need a trusted identity in the OpenPGP web of trust therefor.
Keysigning Parties and Meeting People for Keysigning
If you are living in the "middle of nowhere", you will very likely have to get out of there. Attend meetings with key signing parties, expect such especially at free and open source software conferences. Again, if you for example want to get closer to the Debian community, join a Debian meetup. Chances are good you can find people for key signing there.
There is a (rather outdated and rarely used) directory of people willing to meet for key signing: http://www.biglumber.com/ (but experience shows that lots of entries are completely invalid by now, and only few actually respond).
Finally, there are some "certificate authorities" (although OpenPGP does not really know this term): I know of CAcert which also signs OpenPGP keys (but again, you will likely have to travel to meet people to get CAcert-assured), the German Heise Verlag with its "Kryptokampagne" and if you have a German ID card, there is a service by Governikus that uses the electronic functions of the ID card to verify your identity.