A nice idea, but in the end I suspect the tricky part is the definition of "essential government services" and the criteria for determining whether a person or corporation is "hurting anyone or the environment".
But what are you trying for? The definition of the statement in your mind is clear but it doesn't mean a damn thing.
I think we should aim for the government only providing essential services. But one of those services is making sure everyone has healthcare insurance available to them at a rate that they can afford.
You and I know probably agree on very little about the size of the government, even though we both agree that the government should aim to provide only the minimum essential services.
I know, I'm just saying it would be a whole lot better to have this debate and take whatever comes out of it than the current situation, which is mostly cynical and corrupt sociopaths on both sides who aren't in any way interested in bettering the country.
In other words, I'm just as happy to see someone like Dennis Kucinich do well as I am Ron Paul, even though ideologically I agree more with Paul. I think we should be more concerned with replacing evil people with good people than the particulars of one platform or another. The common grounds (stop the wars, stop corporate welfare) are vastly more important than the differences like health care or welfare for people who actually need help.