I managed to patch the deployed service and set

spec.loadBalancerIP

after the deployment, but I am trying to do this in the helm chart.

Try something like this

def fix_service_namespace_rapid(obj):
    if obj["kind"] == "Service" and obj["apiVersion"] == "v1":
        try:
            obj["metadata"]["namespace"] = traefik_namespace_name_rapid
        except KeyError:
            pass

So you are suggesting that I run this on the service after it has been deployed

I suggest using something that is called "transformations"

traefik_chart_options_rapid = helm_v3.ChartOpts(
    chart='traefik',
    namespace=traefik_namespace_name_rapid,
    values=parse_yaml_file(traefik_values_file_rapid),
    fetch_opts=traefik_chart_fetch_options_rapid,
    transformations=[
        fix_service_namespace_rapid,
    ],
)

ah so still in the helm chart. yeah, I will give it a try