Get a piece of 1 1/2" angle and mount it to the bolt just to the left of your yellow circle in the first pic. Make it long enough to span across to the bolt opposite that one on the other side of the radiator then mount some lights to it shining through the rectangular holes in the front bumper. Thats where mine are and it works perfect. You might have to relocate the license plate down onto the front valance to unblock those holes.

 

You can use a solenoid if you like. You got the big terminals correct. One of the smaller terminals is for +12V to turn the solenoid on (not a ground). The other small terminal isn't used in your application. The solenoid gets its ground from the mount so make sure you mount it to metal.