I grew a sungold cherry tomato (orange) through the winter last year and took a cutting this spring and that plant is growing fine after being through many nights in the 50's or below. I also have a Jelly Bean Hybrid from Totally Tomatoes (red) planted from seed this year that along with the sungold is showing no ill effects as the temps are getting cooler during the evening.
I don't think 50 degrees will be too cold for your plants, just my opinion, good luck!