The plan is to mount motor also for the rear wheel to climb the uphill better.
I have ordered a new motor controller and display module. We have investigated the interface between them.
The communication is UART with 9600 baudrate.
Looks there is enough place behind the battery pack for the rear controller.
The controller almost fit.
If the communication is broken from controller to display,
the roller works further properly, just the information from controller is missing on display. E.g. speed flashes. This means, if I connect the two controllers to the same display interface that way, that rear controller transmitted comminication wire is not connected, the two motor should work well. Just the displayed current consumption value will not be correct.