reversed polarity

here is what i did in my van, i get caught working at night a lot especially with daylight savings, so i need light to find parts etc, festoon cool white in cab and 27 watt led floods in the back

hey guys, got my new 2500 and absolutely love it, i do have a question regarding the built in 150/400 watt inverter, i am aware that the 150 works while driving but the 400 ( rear ) is automatically disabled when taken out of "park ". is this normal, can it be bypassed somehow to work while driving, purpose is to charge my cordless batteries while on the move between job sites. any input will, thanks