I see the following two ways one could think of as what "Physics Stack Exchange" might be about:
Physics Stack Exchange is a platform to ask questions about mainstream physics. Questions should ask about the concepts of the mainstream body of physical theories or how to probe them, which means that ideally, every question has a definite answer.
Physics Stack Exchange is a platform to ask questions about mainstream physics. All conceptual questions when studying physics are allowed.
The first one actually describes the status quo and is a "physics based"-approach, while the second one is a "physics education based"-approach. Let me quote John Renie's answer above:
A good question and answer for this site will be one that future generations of physicists¹ will benefit from. That is, having encountered something they don't understand their Google search will lead them here and they'll find the answer to all their problems.
Here is my problem: A question about the rigour in mathematics or what one should focus on when learning theories is something that many (future) physicists stumble upon and need an answer to. This is also something all physicists have (at least implicitly) thought about at some point in their life. Ergo, many (future) physicists will benefit from answers to the question.
Questions about how to do physics are in principal a matter of philosophy. This does not mean that anything goes - quite the contrary - but it does mean that most users and even most expert physicists will be unfamiliar with many aspects that good answers should incorporate. On the other hand, (mainstream) physics is what physicists do and not what philosophers want them to do, so the answers, while lacking in certain aspects, could help students assess the situation.
The easiest possibility is always to just refer every question that touches about philosophy of science to philosophy.stackexchange. There, we have the experts. The problem is that the experts in philosophy might not know how it is actually implemented in reality.
The Q&A-format can support questions about how things are done. They will generate a lot of bad answers (and one will have to enforce rigid non-discussion policies) but the mere fact that we allow for several answers to the same question and we have a sorting by votes means that meaningful answers will be swept to the top. We might want to have a tag "opinion-based" with a similar disclamer as the "resource-recommendations" and we would need to adapt the close reasons.
In order to illustrate what could be possible and might help physics students in understanding the field (although the answer is far from good - it would definitely need to elaborate and explain the last paragraph and even then, I'm not quite the expert on the matter that I would like to be), see this answer of mine.
Where to draw the line? Questions about how to write a paper or how to collaborate with other people are clearly off-topic - they are not about conceptual questions when studying physics. But many cases will be borderline, so this needs some discussion.
Therefore, those questions could be made on-topic, but we should create a special tag and special implementation rules.