I am an academic, but in the social sciences, so I will defer to the science YLFers about mixing separates (in my discipline, it would be perfectly okay to be in a full suit, or separates like a jacket and pants/skirt, or a structured dress/jacket combo). They know what they're talking about! I would think it would be relatively straightforward to buy some gray pants and a black jacket, or something along those lines. Pants do make it easier in terms of comfy footwear, weather conditions, etc.
As others have mentioned, the challenge is that interviews are a two-day marathon! It can be tricky to look professional, be comfortable and ready to walk a bit, not look overdressed or like you're "trying too hard," etc. I wore a full pantsuit on the day of my job talk (always the first day of the interview, as I recall), then some dressy trousers and a blouse (with a sweater or slightly more casual jacket, as I recall?) on my second day.
Of course, what you wear shouldn't make or break you, just be the icing on the cake. You want to be comfortable and feel confident and like yourself. We interviewed a woman wearing a snakeskin patterned jacket and matching pencil skirt, in some sort of poly blend, from the look of it. The jacket had a collar and a zipper up the front. Very memorable and pretty out of the ordinary :). She was invited to campus for an interview and she got the job, and I don't remember anyone on the search committee even mentioning anything about her appearance.
Good luck to you!