The plumbing shouldn't have been complicated, simply a valve at the back end of the tender connected by a hose. The shop forces could have accomplished this without working up a sweat. When No. 18 was on the Grand Canyon it was getting water from a tank car on an adjacent track when the train was being prepared at Williams, AZ. In this case a gasoline-powered pump was used.
When the 18 was at Alamosa I noticed a patch where the valve on the back end of the tender used to be. Since there was no patch on the back of the narrow gauge tenders and there had to be some jockeying to fill the 463's tender from a water car at Big Horn in 2013 it got me wondering.
We don't need to start using auxiliary tenders now.