timer circuit swich swap

Wire out from the board holes, you only need one side of the switch,also like I said that relay is capable of driving the heating elements, that board should have pos/neg switching by adding/deleting a transistor, make sure you pos switch it.

what do you mean by pos/neg switching? and how do i make sure it's positive?

The instruction/construction guide will give you details on trigger polarity, the switch, if you wish to use its illumination will have a pos. output. second way to do this and much cheaper would be to have a pos going momentary switch going to a latch relay, then use ign feed to relay's other coil. When you switch off ign, that wire will go neg and shut down mirror, also wire  12v LED in par with output to mirrors.