Done. Solved with Automator!
This doesn't help people on windows though.
On windows, you can accomplish the same thing by adding a shortcut to your file (FMP URL shortcut works, or a shortcut.fmp12 file that launches your remote file and closed itself out), to your startup folder.
Here's a quick video on it:
I have struggled with this too, and have tried using Automator.
I have not had success.
Could you please give me some more detail as to how you used automator to achieve this.