#53 contains 2 issues, it will be easier to follow them like this.

An other option that came to my mind, which might fall out of the scope of this bundle and would only improve things for those with other than Local backends is that the tmp backend could be also used as a web-server too, and upload instead of actually uploading could just give them information of the file, such as the key and so. Maybe the upload should rather call a handler as the validation does (except using only one) and if there is no handler fall back to the default? Using that one could create a background job that would copy over the file to the desired location, looked it up in the database, changed the location for it and then removed it from temp.