Invoking protected method in C# - reflection or separate derived class?

I have recently found myself in need of calling a protected method from outside of the class (short reason why: I needed to stop the object from firing OnValueChanged event when its value was changed and this was only possible via its protected Set(value, sendCallback) function).

In the end I came up with two solutions:

1.) create a derived class, and only add this function:

public void SetValue (float val, bool callback) { Set(val, callback); }

Luckily, the class was set as inheritable, so it worked.

2.) Use reflection and extension methods and do this:

public static void SetValue(this Slider slider, float val, bool callback)
    {
        MethodInfo sliderSetMethod = slider.GetType().GetMethod("Set", BindingFlags.NonPublic | BindingFlags.Instance);
        sliderSetMethod.Invoke(slider, new object[] { val, callback });
    }

This worked fine as well. Is there any reason why I should use one or another? Both of them are working fine for now, but they are obviously not really clean solutions, so I would like to know if any of them could cause problems in the future.