The plan is that the device will connect to every hotspot it passes.
Not likely. My hotspot is not going to let your wifi device connect, unless I authorize it, by giving you the necessary key.
Sending important data through an unsecured connection doesn't seem like a good idea, to me. And, there are fewer and fewer unsecured connections, as people wise up about the risks (and costs) of allowing unsecured access to their wifi devices.