H2 camera installation

[FiremanJay]

Just got my H2 camera going to install it tomorrow. Since i wont be tying into the trailer wiring like the instuctions say.(have the off road lights installed on the grill)
i would like to make it possible for the cam to come on with the reverse lights, which i will tap into that wire at the back of the vehicle so when placed into reverse it will activate monitor (which is my nav screen.) Also i would like to place a switch in line somewhere to activate the system while driving so i can see whats behind me. The system has a 12 volt acc. wire as well as a 12 volt wire for the reverse lights and a ground. should i hook up a relay as well as a diode and does anybody know the best way to wire the relay so when the switch is on the power wont flow back to the reverse lights and turn them on while driving forward. im usually pretty good at wiring but i am having a brain fart as to how to wire this up
thanks