You should be able to divide the frequency by setting it up for Center-Aligned mode. Try my example for 19.455kHz, change PTCON0 = 0 to PTCON0 = 2.

That should give you roughly 9.7kHz, and let you keep the 10-bit resolution.

At least that's my guess after reading the note just above table 18-2. Seems like it would work just fine, and you can keep the 20MHz osc. If this freq will work for you?