dome light issue

Long time reader, first time poster. This has me stumped!
I have a late '80s GM SUV and here is what I want to do:
To put a switch at the the tailgate the controls the dome lights independently as there is no switch for dome lights when gate is down with doors closed and while keeping regular door switch and dash functions.
Problem I have is dome lights are 12v hot constant(orange) with door switches that ground out. (white)
EX: Door open - white lead cold. Light on.
      Door closed white lead hot. Light off.
      Door open or close orange is hot.

Switch I'm using is a GM factory part and only has two pins. On or off.

Now there is one lead for each color that break into 4 at junction (2 orange, 2 white) due to 2 lights in roof.

I just can't seem to see forest for the trees...I know answer is right there...making me nuts!
I tried switch on every combo you can think of, both fore and aft of junction for dome lights.

Any ideas are most welcome!
Thanks very much in advance!

Is the switch plastic or metal. The metal one grounds when mounted. The plastic one should have the terminals connected when the plunger is extended. On the metal one, connect the terminal to the white wire. On the plastic switch, one terminal connects to white, connect the other terminal to chassis ground.

That was the issue I couldn't get past! Why didn't I see that? DOH!
I was trying to interrupt the circuit with switch instead of grounding at the switch.
Took all of 5 minutes to get it finished.
Thank you sir! Fresh eyes make all the difference sometimes.