The current through your meter can easily be calculated
by applying ohm's law.
i.e if using a 10K pot and 2 resistors of 4K7,
max. current would be 14.4V divided by 10K or
about 1,5 mA.
I am afraid you will not easily find a potmeter that
can stand the vibration, dust and oil present in any
aircraft over a reasonable amount of time.
Also the coupling to the trim cable might not be an easy task.

My approach to this problem would be a series of opto-detectors
and a vane on the trim cable. Each of the opto-detectors
could drive one LED on the panel. This setup has no
moving parts except the vane, does not suffer from
variations in the supply voltage, and offers digital readout
which not only looks cooler but is actually clearer.
Only drawback is the multiwire cable to the panel.
This could be avoided by using more electronics.