I can only join in the advice that you do not do this job yourself. I see so many boy racer cars (rice rockets??) with peeling window tint.
Also, you have to be uber careful not to scratch or tear the tint once applied (obviously it has to be on the inside). I started to remove the dealer sticker from the rear window of our Range Rover and ripped a 4 inch hole in the tint film. £200 ($290) to re-apply the tint.
I have heard mention of a dip solution which does not give rise to this risk. I think Mbenz had his W202 windows 30% blue tinted using this method.
Also, if your local law requires minimum 70% light penetration in the windscreen and 50% in the side glass, that means you can have a maximum 30% tint up front and 50% on the side. The figures you suggested would apparently be illegal. You may not be bothered, of course... (!)
1999 SL 500
1993 320 TE
1986 500 SEC