The switch panel has a control box that you place inside the cab. I have an 8-gang switch panel, they have other options for less inputs. (
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you label each input you have an just use the control panel to turn them on and off. If you absolutely need auxiliary lights to trigger on and off when you put on, say your running lights, or something, then the solenoid trigger method is the route for you.
Military splicing, heat shrink, yada yada, all of that is fine and good, certainly significantly better than those crimp t-taps, but there are more proper ways of handling wiring.