With the first approach, I'm losing all the benefits of server-side testing.
We're considering the second approach, which was our initial idea. However, we need to inform Akamai (before it serves the cached version of the page with the appropriate experiment name and variation in headers) which version of the cached page it needs to serve to the current user. We're unsure how to accomplish this. The implementation might look like:
User > GrowthBook > Akamai or
User > Akamai > GrowthBook > Akamai > User, but how can we achieve this?