KRM --
The switcher project will need to wait for the future. But at least I know what to do with my spare parts! Thanks for the part suggestions.
For now, I need to get the other A unit reversible. I may just harness that to the B unit, since that A unit would need to trail behind the rest. It's the only one with couplers at both ends.
Then I really need to get back to trackwork. No point having nifty trains if they have nowhere to run!