Timmy, thank you for your detailed steps on this. I want to make the switch to dome light trigger for doors off, but I want to retain the original configuration with doors on (ie independent operation based on which door is open). I am trying to think through a switch diagram that would accomplish this.

So far I have:

Doors On
Left step sensor connected to left door signal
Right step sensor connected to right door signal

Doors Off
Left step sensor and right step sensor both connected to right dome light signal

It think I see how to do it with two switches:
switch 1: either the door signal OR dome signal connects to the step sensor
switch 2: either the left step sensor is connected to the left door signal OR the left step sensor is connected to the right step sensor which is connected to the right dome signal

Does this seem correct to you? Can you see a way to do this with one switch?

Any help is greatly appreciated.