I have never found GCWR on the door post. The only place I have seen it is in the Owners Manual.
Years ago, we traveled in a 32 foot fifth wheel towed by a 1994 Dodge CTD standard cab lwb dually. The book said the GCWR was 18,000 lbs. I finally got around to weighing it, and discovered the whole rig weighed over 21,000 lbs!
That's right, I had been driving around the West at a ton and a half over the GCWR! Yet, the rig was under GVWR and under all GAWRs. It was also under the 14,000 GVW shown on the registration.
I did some checking and discovered that every year after 1994 the GCWR of Dodge trucks had been increased, but very little changed on the trucks! It appears that GCWR is a "Mine is better than yours!" marketing gimmick.
I haven't worried about it since.
But, that's just me.