Starting to try and figure a way to handle this that isn't incredibly hacky.
Shouldn't this context be final? I'm hoping so, but it could be that downloadmanager doesn't expect it to... Dunno. Gonna try this and see what happens.
Ok. The principle works and regular DownloadManager still works with the added code when the path is internal storage. Going to spend tomorrow actually fixing everything up so it works as anticipated, now that we know this can work.