Well, thanks for the input gentlemen. Duck season just ended and I thought, for what its worth, I would share my experience.
First, perhaps a creature of habit, I still like the scalding water for cleaning. I tried tepid and cool, but it seemed like the patches didn't slide as smoothly in the barrel. Also I like the assurance of a dry barrel I get from a hot barrel. After cleaning and running patches until dry, I would finish with a pass or two with a patch lightly saturated with bore butter. Perhaps because of the chrome barrels there was never any flash rust. I also took care to be sure the nipples were clear after cleaning, confirming daylight in the fire channel.
Second, the evening before the hunt I loaded the gun without snapping caps. Rather, I ran down the overpowder wad with vigor so I could here the air whistle out the nipple. Of course, the gun was not capped until I was settled in the blind early the next morning. I never had a failure to ignite in 20 or so trips.
Third, contrary to recomendations above, if I hunted consecutive days I left the gun dirty overnight and on two occasions when I hunted three days in a row, left the gun dirty over two nights. I can see no rust or other side effect, but again the gun does have chrome barrels.
And finally, if I was planning to hunt the next day and todays hunt did not end with a bang, I pulled caps and left the dirty gun loaded overnight. Again, no failure to ignite on the three or four occasions I did this.
To be fair, I should admit I took my modern gun on the wet weather days. Also, being in California we are not talking extremes of ice, snow or frozen conditions.