i have a full window kombi with privacy glass, i added an additional midnight tint to the inside. it works out perfect... dark enough not to be a goldfish, but still lets in good light..
plus the bonus is with a hairdryer the midnight tint could be removed later down the line..
as someone mentions if you have a factor privacy this is actually dyed glass... the additional tints are a film..
one word of caution... some things like nail varnish remover or some bug sprays if get on the aftermarket tints will melt the plastic film..
in our volvo xc60 we have midnight tint straight on to clear glass and this works just as well too so don't panic..
andy