I finally stumbled upon the preferred term for the sort of transfer I'm looking for in this network, and it's not exactly elegant: a "data mule." Coined in an article about underwater environmental research, the problem of rapid radio frequency die-off underwater was solved by a robotic "mule" traveling to sensor nodes and waking them up briefly to transmit their data before moving on down the line. The mule could be recharged and sent back and forth, but power on the independent nodes was then conserved until it was needed. The model closely resembles the opportunity-passing ring topology discussed earlier on this blog, so I'll take the term if it's already in use.
But let's face it: "data mule" carries with it some unpleasant connotations of rubber balloons full of heroin or cocaine jammed in uncomfortable places. And it appears that the Flame virus may be capable of doing the same sort of thing on airgapped machines, riding along invisibly on a host USB until it can reach its target. Seems pretty clear that if you have highly-secure data, you should basically just weld shut the USB ports on that machine... but then again, don't forget that "the most secure computer system is one encased in five feet of concrete, powered off, disconnected, and at the bottom of the ocean."
The mule idea, though, also lends itself to a hardy animal that can reach the most remote of locations. Through a service called DakNet, villages far off the beaten path in India and Cambodia are able to get access to Internet communications via a data mule. Still, the implemented solution was on a village-wide level, and required mobile stations located on motorcycles or buses as well as local data kiosks. That level of implementation, though far cheaper and negligence-tolerant than stringing up telephone wire hundreds of miles, is still a bit pricey for the attempt I'd like to make with our project.
So now we at least have a term for our vehicle of transmission, regardless of the connotations. And I don't think I'll blush too much about muling data with painfully-slow connections-- I'll just be hiding the USB in my pocket.