Hearty thanks to all who indulged my no-doubt heavily redundant question. As I suspected, the answer depended on 1) the specific year and model and 2) whether alterations had been made.
I followed the advice from Mavarick: "You can find out in a couple minutes with a VOM attached when you plug in and check battery voltage."
And discovered that there was no difference in the voltage reading at the chassis battery when the shore line was connected and when it wasn't. I think this confirms all the "No" answers in the replies.
On to the next item, whatever it may be. There's always something, isn't there?