D1054
Would this sort of power bogie help?
These are for a Deltic, and with six axle-hung gear-motors in total, it hauls an eye-wateringly long train at 100mph.
The "N20" type gearmotors are nominally 1 200rpm at 12V geared 1:1 to the axles. The plastic cases keep the muck out. Power is via radio-controlled PWM from a 12V battery.
In this configuration, the wheelsets have outside bearing, fully-equalised in the Bettendorf rocker-bogie manner.
By using narrower pinions, maybe you could squeeze in inside bearings and rocker bars?
Like this schematic (for a Mars-Rover):
(Equalising the axle-loads is well worthwhile, because you neither want to stall nor slip any of the motors.)
Bogie and Photo Peter Jackman.
To find out more, infiltrate the Gauge One 3D Circle:
GaugeOne3DCircle groups.io Group
(3D printing is not Of the Essence: just a handy way to experiment - heck, even Peter's wheels are printed!)