Well networking fans, several region and locale issues were encountered. In my area, data-only SIMs were discovered to be unavailable in person. And though they could be purchased online at China Unicom, they were offering only certain types, and not the one that would have suited my requirements (5Gb of 3g data for one year). Inasmuch as the SIM I could have bought offered way too much data per month and cost a lot more than I'd hoped, I caved and bought a phone number instead. 18 yuan per month for calls, SMS, and 2GB of 4g data. On my phone that means LTE.
Bonus news: China Unicom accepted my passport as a valid ID document in the purchase of this phone number.
Why care? Because for various reasons, I had earlier tried a last ditch attempt at resurrecting my China Mobile number. Their office once again lost their shit when confronted with only a passport. They wanted a Chinese ID card or get the hell away and go to the head office. Maybe head office can handle passports now but screw that, I'm with the unicorn now.