The only glass I'd be concerned about would be the quarter windows. On a wagon, they're the only glass that's glued in other than the windshield.
They do glue on from the outside. And of course that's where the tinted glass would make contact with the window frame.
As you said, the edge where the glass makes contact could be trimmed away.
Again, it's sounding better tinting the glass while it's out of the car.
The left and right front door glass tint would have to be trimmed where it slides in the channel. The rear door glass is stationary, so that wouldn't be an issue.
I wonder if anyone lazer cuts tint to fit a G-body wagon? That would make it easier and probably less difficult...not that's it's difficult. It would make it go faster with the pieces already cut out.