I have files buried in long fiilename folders, and I want to have a btm file that uses short (8.3) paths.
I have not an answer, but only a warning for You.
Be careful when You choose the tool and the way of using it, because You might destroy some files on the target.
I saw it happen with robocopy, for example in this situation.
On the source there is a "LongFileName.txt" file, hidden short name is "longfi~2.txt".
There is also a file with only a short name, "longfi~1.txt".
Maybe this file came from a damage that in the past destroyed its long name, I do not know.
Anyway, You start a copy from the source to the empty target.
You copy first the "LongFileName.txt" file, and on the target its hidden short name becomes "longfi~1.txt".
When You copy the second file, "longfi~1.txt", it overwrites the first file.
This might depend on the order in which files are copied, their short names, if You said to overwrite on the target, and so on.
I am afraid that the same might happen for whole folders.