I've added tender pickups on various locos - sometime they are the only ones if I'm
upgrading an old piece. I have had to simply build the mount sometimes. It is a job that
is more annoying than one would like it to be.
Which brings me to my point - finally: at several hundred dollars, even a RK (I'm not picking on MTH) steamer should have 2 pickups on the loco and 1 on the tender. This cannot cost much; the electronics are often in the tender, anyway, on a smaller loco.
It would eliminate approaching 100% of dead spots.
The situation has improved in the last number of years, I believe. Plus, Lionel's big-steam
architecture (separate power pickup paths for tender and loco) and numerous pickups have all but made the problem disappear for them, at least at the high end.