How to wire LEDs to turn on while in reverse???

Searched around and couldn't find an answer

I was looking at buying some LED panels for bed lights and while in reverse for more lighting

http://www.ddmtuning.com/Product-Categories/LED-Bulbs-Lights/Car-Truck-SUV/Panels

How would I wire the the LEDs to turn on while in reverse gear and also be able to flip a switch so that all LEDs are on while the truck is off

Anyone also know what LEDs put out the most Pure White Light for least $


Thanks

 

Put in a double throw switch. Switch up and it is on when in reverse, switch down its on at all times, leave it in the center and its off. Do a search there are plenty of threads on how to wire that up