Validating snowplow tracking has fired without callbacks

We’re trying to achieve an acknowledgement that the Snowplow JS tracker has fired before redirecting our users off domain. The user clicks on an ad off our domain, lands on our domain for tracking, and is redirected to their final destination URL. Our general user flow is the following:

(1) User clicks on an ad hosted externally, no Snowplow tracking on ad click
(2) User lands on “our” domain for click tracking
(2.1) Snowplow initialization
(2.2) Snowplow page view
(2.3) Snowplow trackAdClick
(3) User is redirected to final destination, external to “our” Domain
(3.1) Snowplow domain user id sent via crossDomainLinker
(3.2) Snowplow track Page View fired on external landing page.

The issue that we seem to be running into is that we want to ensure that our Snowplow trackAdClick and Page View fire before we redirect the user to the external landing URL. To my knowledge Snowplow JS pixels do not offer a callback to ensure that we have fired our events.

I found this article discussing the callback feature and potentially adding it to the Snowplow Roadmap:

Have other snowplow users found a way to build a callback like functionality through the JS trackers, particularly involving tracking off the primary domain? I have seen some talk on the Discourse Snowplow forum on the subject but haven’t seen any conclusion or resolution. Thanks!