I think that implementation of this is no more than one hour of your time. Will $15 be enough to compensate this?
Do not worry, I'll add the feature. However you are always welcome to make a donation :-)
This is done for large files (to allow resume). You may force this for all files in configuration.
The only thing close to this description is "Enable transfer resume", but it does not help me. What exactly do you mean?
I've meant it only as a workaround. When "Enable transfer resume" is on for all files, thay are first uploaded to temporary file, which is renamed to target filename once upload is finished.