I'm with you - "All models are wrong, but some models are useful".

I do think dark matter is tantalizing because it hints strongly that our model needs a fundamental change in understanding at some other level. It just feels like too much wall paper to be adding to the model in an attempt to cover the holes.

Doesn't mean I find any of the current alternatives more viable then our current models.

exactly, so when we attempt to put general relativity into practice at the limit of its predictive capability, we may see something is very wrong, then extrapolate a better model, and a few decades later everyone will look back on general relativity as an example of science's ability to carry us away from grossly false beliefs. as with epicycles. and maybe dark matter.

Theories, sure, but knowledge is not confined to theories, i.e. isn’t there positive knowledge, a.k.a. “facts”?

Yes there are facts. I.e. there is a particle called electron, there is a Sun, Cosmic Microwave background, Milky Way galaxy. I'd say those are facts. But I do think the boundary what's a 'fact' vs model/theory dependent statement can be different among different people.

There are theories with super high levels of supporting evidence, so we treat them as true.

This isn't to say that is a bad thing, it is a great thing.

I treat them as true because they are true. I guess there is more than one definition of truth.

But I think what you mean that you treat some theories as axioms (temporarily, I hope). It's a great aid in thinking but a great source of confusion for newbies as well.

There are absolutely multiple definitions of truth. "1 + 1 = 2" is not true in the sense that "Paris is the capital of France" or "Water boils at 100C" are true.

Outside of mathematics, not really. Special relativity and QM proved that 300 year old "facts" were actually subtly wrong, for example.