If you really want to do this here is how I would try it.
1) Run a second set of wires to the battery for the ignition. Run these wires all the way to the battery connection with a separate switch .
2) From Radio Shack get two ferrite chokes. Put one each in both the positive and negative lines to the receiver.
3) At the receiver install the largest electrolytic capacitor you can find in parallel with a 0.01 uf ceramic capacitor directly across the input power.
4) let us know how you make out.