Given the limitations of all the input options of the gear you mentioned, you'll need an audio signal merge device to offer the possiblity to insert two inputs back into the FX Return jack of the Fender Hot Rod Deluxe amp.

Like a Y-Adapter (a bit shoddy, but it'll work). You'll send the M13's Output/Cable #4 and then plug your backing track device's output into the other input jack. It'll be a mono signal, though.