Many good points have been raised here.

Radiator fan blades do not go well in water, but if you remember to enter the water slowly (very slowly) you should not need to modify the vehicle with a cut-off switch. Imagine switching it off inadvertantly - or forgetting to switch it back on !!!

Drain the differential oils after water crossings –very important! You can install extension tubes on the differential vents (transfercase breather tubes) to help prevent water from entering the diffs but regularly changing the oils is still a good habit.

Be wary of currents, if the water is moving, don’t enter, the force is unimaginable and will sweep away your vehicle with surprising ease.