My Tradewind has backup lights. Your Overlander should have them as well. My manual shows only one type of housing for all the trailers that year.
I put new cans in the housings in my Tradewind. In order to ensure a good ground I soldered ground wires to the cans and ran them down to a body/frame wire in the bath.
Good luck with your rehab,
AirForums # 2806
WBCCI / VAC # 6411
Not All Who Wander Are Lost.
Avid supporter of trailing edge technology.