There are certainly some tricks to getting the best from this style, and a few oddities about it. I explored some of these last year. I do like the overall look of the style though - so straightforward and clear (though that may be the hex-board wargamer in me, as much as the role-player).

I seem to remember one old west town painted mostly red... [Clint Eastwood movie reference 😉🤠🏜️]

Yes, you can change the X and Y scaling for symbols very simply. When you've picked a symbol, just right-click to call up the Symbol Parameters pane as you would if you wanted to change the scaling ordinarily. There, you'll see an empty checkbox for "Independent X and Y". Click that box, and try whatever scaling seems appropriate for each axis - this is almost always trial and error, so you just need to persist. I usually find that what I thought should be the X axis is really the Y, but that's likely just me 😉...

I don't think there are any symbols that will do this for you easily, so you'll need to draw most of it. Thus you can just pick whatever style seems best to you for the look you're wanting to achieve.

As your initial drawing shows though, even a simple pit will give you a template from which to work with for this, although it may help to pick a spiked pit to assist in getting the descending pillar polygons to look right at their various angles. The wall lines alone help with those near the pit's edges, after which you simply need to adjust the angling as you work inwards. There's a spiked pit in the standard DD3 symbols, for instance. To make it rectangular, simply set different suitably-sized X and Y coordinates when you're adjusting the symbol's size. This will produce distortion (especially of the spikes), but as you're just using the symbol as a guide for drawing to, that shouldn't matter much.

The pillar polygons will need some shading applied to make it look like they're fading away into darkness (like the pit walls in your post here), which can probably be best achieved using additional polygons drawn over the "lower" parts of the pillars (try the darker Solid bitmap fills that have various transparencies built in), coupled with some edge fade effects to blend one to the next (you'll need to set up several extra sheets to get this to work well enough). It probably won't be quick or easy to do this, because you'll have to keep stopping and thinking about what to do next (I know I would, which is what I'm basing this on!).

If you get stuck, just ask again here. Or maybe someone else more technically adept will come up with a much more elegant, and swifter, solution in the interim!

We've had repeated discussions about submarine mapping styles on the Forum here. I've tinkered about with existing styles and a few additions of my own for use in the Community Atlas. I'd definitely love to see someone tackle these more fully, but am far from sure it'll happen in the short-term.

The main problems revolve around not having access to the same kind of imaging you can get easily for surface landforms, so it's much harder to create artistic symbols and fill styles, because these simply don't exist, and never have done. The Tharp style is fine, but essentially, this is all there is to draw upon of this type for the deep undersea environment especially, and it falls apart as soon as you try to use it for areas less than oceanic in scale, primarily because the detailed mapping to help also to a large extent doesn't exist (plus these maps are interpretations of instrumental readings, such as sonar, which don't give the same impression you would get if you saw the features in reality; the Tharp maps are calibrated and redrawn artistically to fit with more familiar visual landscape impressions - like using wall shadows in dungeons, say, even when you know those couldn't be really there).

There are undersea features that have no land-based equivalents, such as seamounts, trenches and mid-ocean ridges, much of which remain remarkably poorly-understood, often because the areas are difficult to access and impossible to image visually on anything beyond a very limited scale. Even trying to find a reliable drawing of what a single, fully-grown giant kelp looks like (they're usually far too big to image, at up to a couple of hundred metres in height), proved a nightmare when I tried to do so some years back for my Atlas symbols. Photo images show only bits at a time, or from oblique angles, because of the size issue, and the fact they grow in dense forests commonly makes it hard to tell which bit belongs to which kelp! It is possible to make an artistic interpretation, much as the overland styles often use slightly vague interpretations of trees, and it's that "vagueness" I relied on, certainly!

So yes, one more vote for more undersea mapping options (though I have voted for this repeatedly anyway 😁) - just don't hold your breath 😉!