The more I have thought about it, the more I am drawn to an "obstaclean" theory of matter. To put the theory as simply as possible: matter is ultimately stuff that gets in our way. Material objects are obstacles, pure and simple. We might want this or that, and so we embark upon some plan, but then - wham! Something gets in our way. We didn't plan for that, and we certainly didn't want it. It's there independently, on its own.
Or, as Berkeley says (PHK 1.29):
But, whatever power I may have over my own thoughts, I find the ideas actually perceived by Sense have not a like dependence on my will. When in broad daylight I open my eyes, it is not in my power to choose whether I shall see or no, or to determine what particular objects shall present themselves to my view; and so likewise as to the hearing and other senses; the ideas imprinted on them are not creatures of my will.
And Huenemann again, on Berkeley:
He might insist that the obstacles are still just further ideas, but since they originate from some independent source that does not regard of our own wills and desires, they gain a "stand-alone" significance that marks them as material objects. He can insist upon their ideal nature all he likes, but if they are obstacles to me, they are material.
And Berkeley in response (3DHP, Dialogue 3):
But if by material substance is meant only sensible body—that which is seen and felt (and the unphilosophical part of the world, I dare say, mean no more)—then I am more certain of matter’s existence than you or any other philosopher pretend to be. If there be anything which makes the generality of mankind averse from the notions I espouse, it is a misapprehension that I deny the reality of sensible things.
And that Huenemann's 'materialism' is, indeed, a flat-out idealist theory, is clear enough:
According to the obstaclean theory, being material has more to do with the role a thing plays in our explanations than any "in itself" quality or feature. When something represents forces of brute contingency in our lives, that makes it material. This is a virtue of the theory, since no one has really been able to describe "matter in itself" to anyone's satisfaction.
Which is what Berkeley argued, and at great length; he just prefers to use other words than 'material' in order to avoid confusion. The only thing Huenemann gets out of not using 'idealism' to describe his 'obstaclean theory of matter' is the illusion of not having to provide a further explanation of the obstacle-properties of objects.