I went out last night - forgetting to check the battery in my GPS (which turned up to be somewhat gone - to the point that I could not get the unit to calibrate) so I winged it. I stitched using 15 second exposures (20 seconds started to trail) at ISO 4000 using the Sigma 18-35 at 18. The area closed before the Milky Way really was able to get up in the sky, so my son and I found another spot - not as good, and made the best of it.
The first image was about 9.45pm and the second was about an hour later. We left just as the moon was coming up. What I was really going after was the first image's landscape paired with the second image's sky and MW.
Post processing for what ever reason is difficult for me in astro. I'v got it down to a workflow, especially with stitching. Microsoft ICE I have found, does not lend its results to good post processing, so I have post processed one of the panels in LR, then copy pasted the workflow to the other panels, exported in TIFF, stitched and then brought the result into LR for just minor adjustments - cropping, etc. It's not the best, but so far this is the best that I have been able to go. I have to learn Mike's approach.
I also think that I need a darker location.