If you plan to spend a lot of time driving in the highlands it's a good idea to bring waders and a yard stick along on the trip. If you aren't sure by visually inspecting the river them wade across before you drive. If the current is strong tie a rope to you body and use a yard stick to brace yourself and poke the bottom. Remember, if the river is difficult to wade, it is difficult to drive. Please remember there have been some very serious accidents and deaths in those rivers so be careful.
Most people do.
But if something goes wrong you may find yourself stranded in a very remote place. It is therefor necessary to bring along warm clothing and extra food. Also make sure you have enough fuel to last your trip including unexpected delays. Spare tires and common tools are a must. Ropes, a shovel, waders, a yard stick and gloves.