No pictures, because I was darned busy yesterday, but I have it all together and working "ok". I have a tight spot in the passenger side channel which needs to be expanded to make it uniform.
There are definitely some tricks that can make this easier.
First, it can only be installed in one order. 1. Regulator 2. channels 3. glass. Trust me, I tried various ways to get everything in there, and I doubt it can be done any other way.
Mine has the safety switch already disabled, so I could operate the window with the tailgate down, which made it much easier. I hooked the regulator up to power first, because it's a lot easier to get out if you disconnect the bolts with the arms in the "down" position, and then once you have it loose and in position to pull out, you carefully put it full "up" and it pops out through the center hole with a touch of maneuvering.
The installation involves a bit of spatial reckoning. One of the roller channels needs to be removed from the bottom window channel/gasket, and you can't install the glass with the channel/gasket already on. Of course, that gasket pinches right where you cannot see or reach. I used a long flat head screwdriver to blindly flail at it until the window felt like it was fully seated along its full length. It helps to know and use your best swear words for this process. (One issue is if you live next door to an elderly, retired Baptist minister, who likes to come out and watch.)
The big/long screws on the drive gear cover keep other stuff together on the side opposite, so be careful when you remove them.
If you run the window regulator all the way up for removal, the drive gear will disengage from the driven teeth. This will cause puzzlement and make you wonder if you broke it/screwed up. All you need to do is to push on the arm until it engages the gear to correct this issue.
Once everything was installed, I ran the window all the way down to be sure the glass cleared the tailgate completely before fully tightening the four bolts securing the regulator to the tailgate. If the glass still sticks up, you move that part of the regulator down and tighten down the bolts.
Now, both my key in the tailgate and dash switch work. Just need to fix that slight binding issue and I'll move on to the next issue.