If the shadows are darker than you want, you should try Magic Lantern. The Dual ISO should help. ML is very stable. I have it permanently on my 5D3.Any advice on how to get the most detail out of clouds?
Expose to the right, focus at infinity, stop down to your sharpest aperture and try to focus on an area that has relatively low contrast. HDR makes everyone feel free to go nuts, but any decent landscape photographer knows that the best light isn't sunset, it's just after... "Flat" lighting can be your friend. Exposing for the foreground and clouds is tough so just go with clouds if you want clouds, or if you're lucky enough that they meter in the same range (or the sky is dimmer!) go nuts with foreground. For this of course I use my spot meter (sekonic because I can't afford pentax).
If the cloud cover is evenly lit, awesome. If not, you can use a long lens and isolate one part so the scene DR isn't too crazy, then crank up the contrast in post.