Sunset time lapse questions

I am trying to figure out how best to create a time lapse of the sunset or the sunrise.  The experiment last night showed that I don't want to start a sunset while the sun is still up.  What I did was shot 1800 frames at 2 second intervals, 1/200s exposure, f/7.1, ISO 100.  This was roughly the correct exposure at the start of golden hour or about a half hour before sunset.

Then I exported them from LR as TIFFs, imported them into Premiere Pro, and added them to a time line.  Each photo was one frame in length.

The frames were totally black after about 45 minutes.

The biggest "yuck" is that the resulting video has the leaves of the foliage dancing around as you might expect from footage with a super fast shutter.

One idea would be to have the shutter open for 1s (and still take frames at 2s intervals).  This would give me the typical 180º shutter.  I think I'm also going to start just at sunset.  And also take sets of frames adjusting the exposure up (more exposed) slightly as time goes by.

I can't be the first adventurer into the idea of a time lapse sunset with foliage in the scene.  What are some of the other tips I could use to get a nicer final result?

I'm wondering if I could take half as many photos and then ask Premeire to render frames inbetween each of the photos but I don't know how to do this or if it is even possibe.