whalesurfer

I might sound repetitious but personally I think attending job fairs might be your best bet. Jumpseating won't help you much since you aren't really flying but merely riding as a passenger. Even if you were to hit it off with the crew no one would ever take a recommendation written for a "great jumpseater" seriously.

However, the fact you worked here in the past is huge. Hopefully you left on good terms and maybe you still have contact info for some of your previous supervisor(s)? I'd ask them all to write you short, one-page long recommendation letters explaining why they think you'd be a great pilot for ups and then take those recommendations with you to a job fair (make copies for later). The HR reps you'll meet there have all done the same type of jobs you did back then and they do love "people who threw boxes" in the past.

Go to a job fair and basically say what you said here, "I live in an area where most pilots end up flying for passenger/other airlines and I haven't had a chance to network with UPS pilots BUT I'm a former upser and this is why you'd love to hire me as a pilot."
Then give them the stack of your letters. HR reps are humans and hopefully they'll connect with you.

In the meantime, keep networking because nowadays with all the social media available to us you might finally find someone you flew with in the past who actually works here. Ask your Facebook friends if they know any ups pilots and if not if they could check with their friends? It might be someone you lost contact with who you think flies for brand yxz who's actually working for us now?

So don't give up, this is a great time for brownie wannabes because it looks like we'll be hiring for a while. If I think of something else I'll post it here.
I sincerely wish you the best.

Maybe someone else here has other suggestions?