Slide film and sunsets will probably mean backetting, narrow latitude film and the long dynamic range of the scene preclude anything else. Many people use a graduated neutral density filter - darker on the top of the filter, for the sun and the sky and clearer on the bottom for the land or water. You also might want to consider color negative film for sunset pictures.
That said, I find with a spot meter, you can point it toward the sun, but not at it, maybe 15 degrees away, and come up with a good base exposure.
The minolta incident meter is excellent, better for slide film than a camera's built in meter, but, as you know, doesn't work when a light source, e.g., sunsets, stained glass, is the source of the picture.
Hope this helps,
Take care,
Tom