I used Nightshade on both my (ex) explorer and my buddys Dodge ram, and as long as you do THIN coats and take your time and make sure you use alchohol to clean the surface then rub it with a towel to get rid of any residue before you use it it works great. I didnt scuff the the tails either, just made sure there was no oils or any thing on them then just sprayed the nightshade on. THey looked very clean, shiny not matt but if you want matt all you have to do is back off a lil so there is a lil more "overspray" i guess you could say. If you can I would recomend practicing on something like a spare or a trashed tail light or something before you do yours if your worried about it.
Both my Explorer and my buddys dodge turned out great. Before I moved he told me he got asked all the time where he got his tail lights tinted at. 3 coats was enuph to get them dark but not black, but 4 coats i think would have almost blacked them out. Im actually thinking about buying some new tails for my Ranger and doing it to them but first I need to do some other stuff to the truck before I put money into that.