I did 20% on the front and 35% on all rear windows and think its about as good as its going to get. My tint guy said the rears glass has pigment in it making it hard to match. Don't think its too dark either.
Here is a photo. https://photos.app.goo.gl/AJdAzMD0nV2UQtT12
Sorry don't know how...
Could just buy these black silicone covers. The 19mm fit perfectly and look great. A removal too will need to be purchased separately. Can be found on eBay for $1
http://r.ebay.com/Ou89mA