Apologies for the late reply, but doing some research on this matter, I found this following mention : custom headers/query parameters on server-side requests are being ignored, it looks like custom headers would not be rendered and this is currently not possible.
I wasn’t really able to find anything that might assist with this implementation, unless I am missing something, in which case I do recommend submitting a Feature Request where others can vote on the feature. The Product team monitors this category and if there is enough interest, it can push for further development of the feature.
Don’t hesitate to reach out to us for any further issues/discussions!
Have a great one,
Gerald