Friction shouldn’t be a problem because it is an actual roller, there’s a smaller tube (shaft) inside the one you see. After painting I may squirt some molylube in there to grease it.
In terms of construction, the shaft goes through the hull so it’s pretty sturdy.
I only did this to one side so far to see how it works. There is no drift when driving it, so I assume there is no drag or strain on the motors.
Great points, Thanks.