A few questions, if I may...
Less than 20Z between embark and SMR.
Can you do this in worldgen, or just using dfhack to find a good spot, with a 'short' world? Even with minimums between layers and 1 cavern layer, 20Z is awfully short. And, do you use agriculture and trade to get necessary materials? I can have issues mining out enough with 50Z embarks, once the fort is a few years old, and usually try for 100Z or more, to have plenty of good rock and ore.
A very small and thin aquifer.
Coming back from not playing in a year or more, I'm finding it hard to find what makes for good aquifers, these days. Are there any specific parameters to increase them, or common parameters that are decreasing them? I keep going to embarks with them only to have to use reveal, and find a tiny little pocket on an edge, if anything, rather than the old entire square, or most of one, filled with water. I'm one of those weirdos that
likes big aquifers and I cannot lie <whip cracking sound>, and it seems that whole-embark aquifers are not everywhere, these days.
Vertical layout fort.
The only way to dig!
Lethal cold and/or lethal hot.
Any tips for getting more glacier and tundra squares?
Personally, years ago I got fast low-latency RAM, and have every intention of spending on that again when I upgrade my desktop, to get a little bit extra out of things. Right now I'd probably get the best 3466MHz DDR4 I could find for a decent price, but with AMD officially showing off 3700MHz and up support, there might be even faster affordable RAM when the time comes. It tends to help out in other city builder and strategy games, too.
Assuming things are like older versions (it seems so), small very specific stockpiles (such as 3x3 with 3 wheelbarrows for heavy items, or plain 3x1 or 3x2 for lightweight items), with well-organized take/put relationships set up for those stockpiles (minimize jobs
and also minimize path distance between common repeating jobs), keeping workshops and their stockpiles out of the way of regular traffic (including just by low traffic, if the fort doesn't go as planned), have as few open paths between fort sections as possible (preferably one, possibly with locked doors or retracted bridges for military or service tunnel access in a pinch), as few squares to path along as possible, as little chance of pathing with a group of other dwarves as possible, and prolific traffic designations (oh, and set the weights higher in d_init.txt), tended to help quite a lot. No stupid dwarf tricks, just limiting production, stockpiling, and pathable networks (stockpiles are a big one, and most stockpiles only need to be production and consumption buffers).
For example, I might dig down such that every 5Z or 10Z there is a potential fort section to dig out, generally with a purpose other than dining or living space, and with only one way in and out. The dwarves working there will also have their own dining rooms and bedrooms there, with small food and drink stockpiles. I have to give in some, with taverns and temples and whatnot, but that alone can keep them from having to path too much and too far (and thus interact with other dwarves in their way), most of the time. Most other dwarves just come in and drop off or pick up something on a different Z-level than the workshops or bedrooms, or the workshops will have output stockpiles on the ramp/staircase side.