I actually had looked into the tint laws for PA and spoke with a few people not so knowledgeable and a number of people that were pretty knowledgeable. Basically what it comes down to is that trucks and SUVs follow different tint guidelines than cars. Trucks were on their own at first until the SUV started becoming popular then it was just kind of pushed into the same category. A pickup can have any window behind the drivers seat literally painted black and still be legal. The reasoning is because you can load items into the bed and legally haul them that are so big they block the drivers view out that window. Thus there is no issue with tinting the window as dark as you want. SUVs get classed the same.
My Ranger had factory tint on the rear windows. I didn't like it so I put 5% over top of it, which got it almost as dark as I wanted it (wish I would have gone 2.5%). I also put 20% on the doors, which was fine until I got stopped for exceeding the speed limit. Then it became an issue.
My F-150 had no tint on the back glass. I stuck some 5% on it because it's what I had on hand. I still wish I would have just bought some 2.5% for it but I'm not about to rip it off and do it over, I have more important stuff to do. I started putting 35% on my doors but never finished it.
If you have no factory tint on the back windows of the BII, I'd put at least 20% on 'em. It'll help out too if you run A/C at all. Just tinting the back window of my F-150 made a noticeable improvement in cooling in the summer. Pre-cut stuff may be hard to find, but you can buy tint wide enough to do the job, trim it roughly to length, spray the window and stick the tint on there (clear film side towards the glass on the inside of the vehicle) and with care and a sharp razor blade, trim it to fit. Then pull the film off, clean the glass (take care to scrape the whole window with a razor blade to make sure nothing is stuck and clean it good). Then wet the window and peel off the clear backing and fit the tint in place. For doing those windows, you'll want an extra set of hands to get the tint on there. Use lots of spray on the window before sticking the tint on it, then spray the tint to lube up the squeegee and work your way along pushing the water out from between the tint and glass. Best to do it on a cooler morning so you have some time to work with it. Then keep the windows up and let it bake in the sun for a couple days.
For the spray, I just use a regular spray bottle and a couple drops of dawn with clean water. Works great. I also have a couple of the hard rubber squeegees they sell for doing tint and an old credit card for working in tight spots.