That could work. Problem is, you'll get the same results as with SaveDataFiler. The save transfer tool pretty much does what SaveDataFiler does, and because Gateway hasn't fixed the save encryption for gateway mode yet, it won't work either even if it can see the CIA of the game you installed. I had PowerSaves when I dumped my game, so was able to decrypt it and import it into my dump of the game. There's no way of doing this without PowerSaves currently. Sorry.
FYI, CIAs installed with DevMan likely will not appear for the save data transfer tool while in Classic Mode. Though I have not tested this.
You'll need to be Classic mode for the save encryption to work so long as you are on a newer firmware like 9.2 for example.