Just a point of clarification on the above statement regarding keeping the schwintek slides "in" while driving.
This system uses a pair of stepper motors to provide movement to the slide room. The slide will not move out ( or in ) until electrical power is applied to the stepper motors. This is one of the chief advantages of this type of electric motor. When it stops in a given position, and the controller cuts power to it, it won't turn. In this case, this keeps the room "in position".
This is why, if you have a fail mode where the room is "out" ( extended ), and cannot be retracted inward with the motors, you must manually disengage the motors ( the pinion gear ) from the rack in order to physically shove the room inward.
At that point, yes, you do have to lock the room in the closed position with something like a board, or potentially, the above mentioned widgits that are the subject of this thread.
I only point this out so that folks don't feel they have to add something to the schwintek system for normal operation/safe transport of the trailer.
Hope this helps, gw