This isn't exactly what you're showing there, but you could probably use it as a jump-off point.
I ended up getting one of those Japanese one-axle drives with a centered motor, and decided it was pretty worthless. Hung on to it for a couple years. One problem was it always derailed as the flanges were sharp and no taper, picked every rail joint. And, constantly stalled. The turnaround came when I found out I could put in Kato wheels, which were just excellent in quality.
This turned out to be a success, actually. I had to grind out nearly the entire inside of the REA miniatures Burro crane with a Dremel, and scratchbuild a new deck. The motor powers one axle only. It is permanently coupled to a 40' flatcar built out of the frame of a Kato caboose, so it has 8x8 electrical pickup tied to the burro crane. No more stalling. It can push the flatcar around well, and with all the weight from the cast metal crane cab on it slowed it down to usable basis.
I've got some videos of this running on YouTube.
This is the smallest running thing I've ever made, period - much smaller than a 25-tonner.
