Isn't it rather ironic that you cannot propose conditions under which you would be scientifically convinced that an intelligent designer created the universe and sustains it to this very moment? If the idea is so crazy and unscientific, surely you can suggest ways in which that potential reality could, or should, be revealed to an observer. Or is it simply a subject you would rather reject out of hand as unworthy of consideration?
If you designed a machine and then took it into your hands to run it, how much, and in what manner, would you want to make yourself known to the machine? Have you ever talked to a car or lawn mower? Try building one out of scratch and running it. See if you do not have a few words to speak to that scientifically inanimate object. Or would you expect that object to hear you?
It so happens that you and I are not cars or lawn mowers. Is what makes us different beyond the realm of science to address? You may think so. I do not. Nor do I expect the Creator to intrude Himself to the point of absurdity in an effort somehow to "prove" to science that machines do not make themslves.
The bleating is persistent enough: "God is above science, not scientifically accessible, and therefore not allowed scientific consideration." Why? Because His existence is not falsifiable? Guess what. The notion of a 4.5 billion year old earth and common descent isn't falsifiable either.
99% of evolutionism is inferential and based upon circumstantial evidence. To infer from the presence of purposeful biological entities and physical laws that there is an intelligent designer behind it all is hardly unreasonable or unscientific.
The only thing I would leave outside the capacity of science to determine in regard to a higher intelligent being is what that being's personal disposition toward the observer might be. Otherwise science ought to be free to assume an intelligent beings' involvement with the universe or discard such thoughts. Most science takes place without regard to either premise.
The problem is, there is absolutely no way to prove or disprove such a proposition.
So while the charge that evolution seeks to disprove or replace God might apply to individuals, it cannot be applied to science as an activity.
Science does not seek evidence of God. It seeks to discover how things work. It is not science which seeks to find evidence of miracles or signs from God, and it is not science that is disappointed when none are found.
I think you should be ashamed for expecting an enterprise that limits itself to the visible, physical world would be able, somehow, to put God under a microscope.
It is not science that is the problem here, and it is not God that is the problem. You have been warned about demanding signs, and you ignore the warnings. It is you and your understanding that has the problem.