Not wet I don't think?
Many with computer radios will plug that lead into the receiver anywhere and assign it a switch? Others, possibly with older radios, will set it up just like they would for landing gear, using an aux. outlet on the receiver and transmitter switch normally used for landing gear? Either way, make sure you set the transmitter up so that channel gets full travel!
You're also right in that there's no reason to be concerned about dropping voltage to an ign. module rated for 8v.