I believe you have mischaracterized Behe's position. He may well have concluded, based on his observations and interpretation of them, that naturalistic evolution is not sufficient to explain the sorts of large-scale changes one sees in nature. Note, however, that Behe also acknowledges that evolution can and does occur at a certain level.
Clearly there is a balance that can be struck between the two. So I would say that "large scale" is a term that needs to be carefully defined, and you have not done so.
The fact of the matter remains, however, that intelligent design can and does occur on a daily basis. It is clearly not the impossible hypothesis that you make it out to be.
If all it is is that there are things that are designed by intelligent agents and that we can detect such, well then of course that is completely Scientifically valid as long as you are not delving off into supernatural agency.
You're almost there ... but not quite. There's no scientific requirement to rule out a "supernatural agency," either. For one thing, it is as imprecise a term as "large scale." For another, to rule out the actions of a "supernatural" designer a priori assumes that we would not recognize anything that designer did ... but it is not really valid to assume that.
I have provided one based upon Behe’s “irreducible complexity” argument and it seems well in line with what the Discovery Institute is promoting. If you don't like it provide a substitute.
So if one can distinguish engineered human insulin producing bacteria as “intelligently designed”, does that mean that the other bacteria is not designed?
Appeals to a supernatural agency is not and never will be Scientific. Not unless that agency is predictable and measurable; and then it is hardly supernatural anymore is it?
So was Citrate plus e.coli intelligently designed?
Was nylon eating bacteria intelligently designed?
What exactly is your I.D. hypothesis. Hard to address it if you will not state it.