This thread is so large that people either have forgotten some of the picture posts or never got to catch up. I have gutted my inner door panels to the point where I removed about 4 Lbs from each door IIRC and the window regulators and lock mechanisms work just fine.
Some may not do it because of the amount of work and planning that goes with it, but every ounce counts as they say.

When I get a moment, I'll re-post my inner door pictures. The Lexan windows go up and down fairly well with a little guidance when they reach the top channels. This is of course, on a post sedan type of door.
Yes, I've heard that the beams in some cases had to come out in three parts and with care. Spot welds do need to be drilled out.
I removed the ones out of my Diplomat in two parts and it did not take out so much weight, but then again, Dippy doors are smaller than those mile long landscape Challenger and Charger doors.