InfoPath Dev

 Alternatively, if I could authenticate against a data connection using the service account of SharePoint, that would also be plausible solution. I just ideally don't want to have to resort to storing plain-text passwords in document libraries, although it's looking like that's my only option.

I've spent at least 8 hours so far trying to get an InfoPath form to authenticate against a SQL datasource. I've had to jump through countless hoops so far, discovering UDC files, obscure sharepoint configuration options and other unobvious requirements along the way. As soon as I resolve one obstacle, I'm presented with another. ...