iRule to rewrite HTTPS URL

you can assign traffic policy to the virtual server
https://techdocs.f5.com/en-us/bigip-15-1-0/big-ip-local-traffic-management-getting-started-with-policies/introducing-local-traffic-policies.html

the requirements have changed.  Now mgmt wants to change the Host: <name> in the client HTTP packet to a different name, regardless of what the client is sending as a Host in the packet.  So i created this irule, but if there are multiple host header this will replace the last one.

i was looking at the traffic policy, but i cannot get it work, because the host header could be anything.  The traffic policy does not seem to like wildcard characters.

when HTTP_REQUEST {
HTTP::header replace Host "<Hostname>"
}