The trick of phase locking to the IF definitely works. I believe it's
called synchronous detection. One trick that might allow for simpler
hardware would be to use a 5 kHz IF. (You'd need to use filtering or
phase cancellation to get rid of the unwanted product on the other
side of the desired signal.)

It should even be possible to use quadrature detection with the LO off
by 5 kHz, then feed both the I and Q channels into a DSP and "phase
lock" to the IF frequency in software.

A coworker of mine told me about still another DSP trick, where you
tune as close as you can to the carrier, but of course you're a few
hertz off. Looking at an I/Q diagram, the slightly off-frequency AM
signal will look like a rotating vector. So long as there isn't a lot
of noise, the DSP can keep track of the polarity as the phase rotates,
and recover the AM as the magnitude of the vector.

David
--
In electronics, no one thinks you're strange if you blow your PAL.