In k3s how to whitelist specific namespaces to work with traefik?

In k3s how to whitelist specific namespaces to work with traefik? There is an allowCrossNamespace option for traefik, somewhere, helm or just in its plain setup, and I had to have enabled it because there was the UI for one of my services in a different namespace (longhorn), but I dont like the idea of it being open for all namespaces, also that might get messy with multiple ingresses for the future, so is there a way to whitelist specific namepsaces to work cross-namespace?