That's fair enough. But please don't take my statement of "daily Japanese life" too literally. I mean that honorifics don't carry as much weight as people tend to assume that they do. Don't get me wrong -- I did too as a teenager trawling websites and reading about anime and manga. But looking at it from my point of view now (which is, ultimately, just one person's point of view), there are many other and more natural ways of trying to convey that in English.
If, for example, I always called my best friend Tetsuro "Tetsu." Unfortunately, he and I have been growing apart, and slowly this has gone to calling him "Tetsuro," to eventually "Tetsuro-san." This is no different from your childhood friend Davey -> Dave -> David. While you cannot carry that exactly in a translation, you could change the way you write the sentence. 「おはよう哲郎！」and 「おはよう哲郎さん！」 could be rendered as "Heya Tetsuro! and "Good morning, Tetsuro!" respectively.
I guess what I'm saying is that before you start work on something, you need to make a conscious decision on whether you want to translate or to localize. There's no formal distinction between the two, but the former is focused on explaining the nuances and bringing across foreign concepts (at the detriment to flow and narrative) to the viewer, while the latter is focused on bringing across the narrative itself (at the detriment to nuance being lost) to the viewer. A good example is a joke. If you translate it as-is, an English speaker won't laugh because the pun doesn't carry over. If you localize it, you would simply write a new joke to make the viewer laugh. So was your objective to explain the words of the joke, or to make a person laugh?
That's what should be decided.