Actually, I don't remember much of TV operations (vacuum tubes were still used when I last worked on them) but, I still remember the screwups (blowing up electrolytic capacitors, smoking resistors, etc) and changing the coil leads, on the TV, was a screwup.
I, myself, am planning on finding a used 5" TV and dedicating it to just the backup camera.
You might be able to use the DPDT switch if you turn off the TV prior to switching it but, do you want to chance it.
BTW, I really think your bus looks great. You have done a lot with the bus and done it at low cost and with good taste.
Now, if I coulld only be blessed with your scrounging ability.