I'm planning to add a keep-alive to a small tank locomotive.
The keep-alive will be hidden in a tender, and I would like to have a backup light on the tender as well.
The locomotive's stock decoder has an embedded sound module, so I'd rather not replace the whole board,
but the decoder does not have an output for a backup light either.
In addition, I only want to run two wires to the tender to simulate air and fuel lines.
(It will be an oil tender)
My proposed solution is to put a mobile decoder in the tender, that uses the same address as the locomotive,
with electrical pickup from the tender's wheels.
But I don't want the backup light to go out over un-powered turnout frogs or rough track,
so I'd connect it to the keep-alive as well since there isn't room for two keep-alives and a decoder in the tender shell I want to use.
Will this plan work if the two decoders are wired in parallel?