You'll probably need to look elsewhere. Say, electric golf carts.
Adult Trikes don't use differentials.
They just drive one wheel (usually the right one) and let the other side freewheel.
Similarly, they only have brakes on 2 wheels -the front, and the Driven rear wheel (one side only).
also consider:
Recumbent Tadpole Trikes, which use 1 large wheel in back, and 2 small wheels in front. Also avoid the need for a differential, since only the single rear wheel is driven.
They then have various braking configurations, one of which is to have separate brake control for each of the 2 front wheels to enhance steering. Tho others control both front's simultaneously with the rear wheel separated...
Maybe you should consider a Tadpole wheel configuration? it works for Trikes, avoids the complexity of a differential