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Gadget...What you are dealing with is high contrast imagery....that is, you have a very bright sky and a very dark foreground. Unfortunately a camera cannot read the entire dynamic range of lights and darks that our eyes can. This means that without some sort of enhancement, such as a filter or combining bracketed shots (HDR techniques), you will not be able to get both sky and foreground in correct exposure.

Understanding this limitation, here are a couple comments.

Long shutter speeds will not result in over-exposure if you have the proper aperture and ISO settings for "that" exposure. Actually it can be said that longer shutter speeds can result in better sky colors for your type of shot.

I see you used ISO 200, f/1.8, and 1/125th shutter. First, I would use the lowest ISO possible, such as ISO 100. That will give you the least amount of grain and the best image quality. Next, I would also never shoot without a tripod. It's a necessity.

On shutter and aperture...I would definitely use a smaller aperture, such as f/11 or f/13...for two reasons. First, it will give you better depth of field and thus a sharper image. Don't go overboard...f/16 is about as high as I go unless you know your lens and it's diffraction qualities. Second, a wide-open aperture, such as f/1.8 as you've used, will give you harsher color rendition and saturation and will exaggerate your over/under exposure predicament. I would not use a wide-open aperture for any circumstance unless you have no choice, such as a really low-light indoor event where flash is not possible.

Finally, I would use your "shade" white balance setting which will give warmer results...or custom set to the scene. Of course with RAW, this isn't as important, but it will give you the preview to know while you are there.