The way that ACR handles output color spaces is similar to softproofing, so if your purpose is to edit an image to sRGB, just set that color space as in you images #2 & #4.
Now, about editing, I would think about two choices:
1.- Edit directly with color space configured to sRGB, so you will know if you are clipping a channel.
2.- If you like to edit in ProPhotoRGB to create a "Master file" and need an sRGB output, then edit in PPRGB, save your edits and then change color space at the end to sRGB (as in #4). If you have clipped channels, a basic approach is to reduce vibrance, which affects saturated colors first.
About your comment that "the majority of out-of-sRGB colors were not in the raw data", well, that is one thing normal in editing, just adding saturation could make colors go outside a small color space like sRGB.