How do I create an HDR shot that avoids any highlight clipping?

I’ve taken three bracketed shots with a lot of contrast between the sky and the mountain valley below. Now I’m trying to create an HDR image which includes all the details from the clouds above without highlight clipping and likewise all the details from the forest below.

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However currently the best I can do in Lightroom is this:

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As you can tell, there is some highlight clipping on the left side of the image where the sun is, even though the least exposed shot does have the non-clipped version of the same clouds. How do I create an HDR that avoids clipping any highlights, even in scenes with extreme amounts of contrast?

If you’d like to download the RAW images above, they’re available here: 1, 2, 3.