I'm going through the same hell with a spare hatch right now - removing that old tint crap is like removing concrete and I've been able to get it off without damaging the rear defroster lines (mostly) with sharp blades and that Gila spray-on remover stuff. It actually works reasonably well given the horrid condition of the film and its age. The few places that did get nicked are going to get repaired - Permatex makes a repair kit, ran about 10 bucks. Once that's done (all tint gone plus the defroster repaired) I'm going to finish removing all that black paint border crap in the areas where it doesn't matter (i.e. never gets seen) and then re-tint and seal with acrylic on TOP of that to secure the edges and restore the painted edges "stock" look

Not to pat myself on the back, but I did a rather excellent tint job on my truck - not a single bubble or scratch after 7 years to this day. The keys are to clean the glass with ammonia about 5 times, trim the edges carefully, use a lot of soapy water to seat the film on, and do it with the glass OUT OF THE CAR. As far as trimming the edges goes, use a fresh razor blade and "scrape" the edge of the glass so that the blade is slicing the film about 1/16 to 1/8" from the edge. If you looked at a cross-section under a microscope, it would be beveled, that way its less likely something will "snag" the edge (like rolling it up if it's a side window for example) and no air can get between the glass and the film at the edge. That's where I've seen most film start to fail. Once a bubble forms there, the film is toast and has to be redone.

Good luck to all, and I'll post pics when done.