the issue in the original post is to not have custom data source appear as "User Defined 1" in the "Device Type" dashboard. The correct way to resolve it is to rename "User Defined 1" to something meaningful. The "Device Type" dashboard doesn't use CLASS as filter.
That's true. I was just wondering if it fixed the other issues with locally defined devices. The ugly workaround I proposed lets the device integrate into predefined views where device class is used and it does give you a name for the device - but the wrong one. It also appears to allow the Device Type ID filter to be used as designed.