I have them on mine but used the amber color. Yes they are very visible to cars that are beside you or just behind. They may be to close to see your rear lights but they will be able to see these.
Another option is to replace the mirrors with a chevron of LEDs. Muth is the best known (about $175) but there are other trustworthy sellers (e.g., ebay) that offer a similar product for about $100. These are VERY visible - and much larger light displays.