This is not a good plan. You are almost certainly better off with Silver, or another Envoy (if you only have 1).
The issue is, if Envoy draws Smithy, you are like getting double hurt here. Additionally, Scout never grabs your Green cards as well as you expect--especially in a regular Province game, when you green but you don't end up with like a million Victory cards until the very, very end (unlike, say, Duke/Gardens/Silk Road).