Actually, you do not want to put the win386.swp file on removable media. Better to delete it in dos and let windows recreate it anew, only to grow again.
From http://www.computerhope.com/issues/ch000358.htm
When storing the Win386.swp file on a removable media device and attempting to eject the storage medium from that device errors occur or the computer freezes.
Because the Windows Swap file is almost always being used ejecting the device or removing the device storing this file will cause errors as it will remove the location of where information is temporarily being stored.
When booting from a removable media the performance tab may show that the computer is running in MS-DOS compatibility mode.
Change the location of the win386.swp file to a non-removable media.