I personally don't like the opto switches, especially the RCXEL unit. I have read multiple issues like yours being caused by the switch. That being said, try the tape on the ignition module and you may want to try different antenna locations. I don't think that the RF is getting into your RX though. It seems to be getting into the aileron signal wires. Using twisted extensions was mentioned and is a good idea. Don't use Hitec Karbonite geared servos on a gasser. The gears are brittle and shear off with vibration. Does this model have rudder pull pull and if so are the cables steel?