You might get a very tasty Americano, but I think it less likely the longer you go on ratio.
E.g. 18g dose for a cup of filter might be around 240g of beverage out (or an espresso ratio of 1: 13.3).
Pulling that much liquid through a traditional espresso puck is likely to result in quite a silty cup (no filter paper, lots of puck erosion, likely a finer grind that the filter brew would use).
But just adding a little more water to the shot, like 1 to 3 times the original espresso shot might open up the clarity, dilute the espresso enough, without making the siltiness so apparent?
When I have had a shot and an Americano of the same bean, beck to back, in cafes (my standard first order) - even when the espresso is good, the Americano is typically dry/dirty tasting, lacking in acidity.