Well, that was 3 years ago. I think the DSB rendering code has become somewhat more restrictive due to other ways it's grown in the meantime. For example, back then, I think I hadn't yet implemented changing the wallset for individual floor tiles, which would be annoying to do at a greater distance. Not that you'd notice it very much, anyway.
The huge annoyance in extending wallsets is that then I have to widen the field of view and figure out what to do with wallitems at those distances. The current implementation in DSB uses the "far wall" that fades to black and doesn't have wallitems displayed on it, because it's basically too dark to see. This is the same wall used in RTC and DM 2.x. This means the only wallitems I need to draw are either from straight ahead or a simple side wall perspective, because, except for these two squares that have no wallitems shown on them, the DM view is entirely confined to a "tunnel" three squares wide. DM 3.x (and old versions of RTC) did show wallitems on these extended squares; they did this weird bitmap stretching thing that worked ok (mostly) with DM's default wallitem graphics, but I'm pretty sure with custom graphics you'd end up with some very strange looking graphics.
And yes, by statically scaled flooritems, I mean pre-drawn doorframes, pits, stairs, and so on. As opposed to dynamically scaled, like items, monsters, doors, and so on.
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