how to manage haproxy route annotations for routes created by IOR?

OCP v4.6.26, OSSM v2.0.4

When creating an Istio application gateway & virtualservice, IOR will automatically create Openshift routes for the hostname(s) specified in gateway resource, which works great.
But: Openshift router uses a default response timeout of 30s, which can be overridden per route using route annotations: "haproxy.router.openshift.io/timeout=2m" 

See docs: https://docs.openshift.com/container-platform/4.6/networking/routes/route-configuration.html#nw-route-specific-annotations_route-configuration

Question is: how can this be accomplished using the aforementioned IOR workflow?

As these gateway routes are now managed by OSSM, and created inside istio-system namespace, we would need to annotate these routes directly during application deployment (when creating/updating appl. gateways but after routes have been created!). This is complicating things and really should be done by the same process (IOR), eg by annotating the gateway - then IOR could annotate its managed routes as well.