The rear light we use is integrated into the seat post, thus a basket on the carrier will inevitably cover the lights. Our integrated rear light is road legal and makes it possible for us to use a fully internal cable routing and the lighting to be powered by the e-bike battery.
The carriers we use are made for pannier bags, for example those using the "QuickLock"-system. Bags such as these can carry more load much more safely than a basket.
If you would like to install a basket onto your carrier nonetheless, make sure to attach an extra battery-powered light onto the basket in order to stay visible.