What must be remembered with regard to vehicles with canvass covers?

For vehicles with canvass covers, two important rules apply:

1. The canvass covers must not obstruct the driver's rear view through the outside mirrors. This is crucial for maintaining safe visibility and ensuring that the driver can see other vehicles and pedestrians.

2. Unloaded trailers with high canvass cover superstructure are particularly sensitive to side wind. This means that when driving, especially on open roads or during windy conditions, the driver needs to be aware that such trailers can easily be swayed by wind, which could affect vehicle stability and safety.

The third option, about securing the load when vehicles have canvass covers, is incorrect because a load in this situation must be securely fastened to ensure it remains in place during transit. This requirement aligns with safety regulations to avoid accidents caused by loads shifting or falling off vehicles. Hence, the correct combination of answers highlights both visibility and the impact of wind on vehicle stability, while also emphasizing the importance of load security.