Yes. I just configured nginx to pass a bogus value and the it came through (not on the instance above).
If you look at the feedback ticket from the thread that you linked, it’s marked as a duplicate of “23891 - Add support for reverse proxies to WE apps” which was marked “Implemented & Verified” in Xojo 2016r2.
I’m building an app that helps simplify deploying Xojo Web apps, it might be of some help 
Public Testing Lifeboat - Deploy to Lightsail or Digital Ocean - #13 by Tim_Parnell