Setting the working directory

You can set the working directory natively, but for some reason it's not supported in the user interface. The underlying .desktop file itself supports a Path key for "the working directory to run the program in" (see the spec) as long as your launcher is an "Application" type.

So just open the .desktop file in a text editor (if you're having trouble finding it, you can create the launcher on your desktop and find it in ~/Desktop, then move it later), and add a line at the end that says Path=YOUR_PATH.

Change the Command to this (substituting the correct paths of course):

bash -c "cd /path/to/directory && /path/to/directory/executable"