As a proof of concept, I did something you're never supposed to do. I edited the real estate data file directly. Sometimes, it's a real pain to try to get items to stack properly. It may look good from one angle, but seams don't align when you turn the camera 90 degrees.
So, although it's probably a bad idea to mess game data, I was curious to see if I could force objects to align exactly as I placed them. It worked. I took eight Ancient Stone Columns and placed them at the perimeter, more or less in the cardinal and ordinal directions of the plot. I saved the yard and then looked for the new file on my computer. Yards are on a 150 x 150 (x 150?) grid, with numbering going from -75 to 75. Editing the file, I set all the Z numbers for these items to the same height. Then I changed the X and Y numbers so that they were exactly -75, 0, or 75. After I saved the file, I reloaded it into the plot (no logging out necessary) and voilà, I had 8 perfectly aligned columns.
I actually made a typo on my first pass. I accidentally deleted one of the quotation marks around my numbers. As a result, the saved plot no longer appeared in the Real Estate window. So, apparently, EQ has some sort of internal check to make sure that the files aren't broken.
One odd finding is that when I saved the yard again, my items shifted ever so slightly, by a few millionths. This is imperceptible to me, but in the actual file, instead of seeing 75.000000, I was seeing things like 74.999586. Perhaps, EQ allows the items to "settle"? Or perhaps, being so close the edge of the plot, perhaps EQ pushes it in slightly? You'll notice that the outlines of the plots are not perfectly square.
This is not something I'd use on a regular basis. But I may rely it when I bring back my "Flyswatter" yard. I had set up a bunch of walls high in the air, roughly in the flight path of spring-launched travelers heading to their plots in the zone. From my architect's vantage point far below on the ground, it's rather difficult to maneuver the walls into place so that they are all on the same plane in all three dimensions. So, I may tweak my numbers to make sure that the walls are properly aligned. Even from a distance I can tell that it's not quite right.
Ultimately, it doesn't matter that much for the purposes of this particular structure as the developers seem to have planned for such naughtiness. When using the spring to launch you to your plot, you are apparently intangible while in the air. So, you pass right through my walls as opposed to going splat. I still like it as a purely visual practical joke, though.
Real estate files are in the userdata folder and named RE_Layout_foo.xml.