It is harder than necessary to separate the electrical harness between engine and tender with the current arrangement. The very tempting side/saddle tank modifications to the 2-8-0 being sold by Backwoods Miniatures (which require moving the board/decoder from the tender to the engine got me to thinking how much simpler it would be if the engine and tender were both fitted with a 9 pin JST or 8 pin NMRA socket and a wire harness with a male pin plug on each end used to join the two. With a 9 pin JST the female plugs could be horizontal and thus keep the wire close to the drawbar. Just a thought.
How about using the drawbar plug-in like the LifeLike Mantua classic logger?