It may be there. You should search more thoroughly.
It was months before I knew there was a strip light in my Kodiak Cub pass through, so you are starting out a head of me. It is possible the switch was pointed out to me during the initial walk through and I forgot. Either way I found out when someone asked the same question you did on this forum.
I was planning to install a pass through light until someone said it was just inside the pass through door a little up out of the way. It was indeed there in the shadows. There are two switches in mine. One is for the under belly lights.
I wish you good luck and happy trails ahead!