Hi Calvin:
Sorry it has taken so long for "someone" to reply; most of us are very busy struggling to adapt to MSFS SDK methods now.
Certainly there is a lot of fun still to be had in FS9 and FSX or P3D (even though Lockheed Martin says its "Academic" only

).
I would recommend referring to this set of data and thumbnails of FSX default scenery library objects (original is off-line now):
https://web.archive.org/web/20210801230150/http://lc0277.gratisim.fr/
Download / extract this ZIP to reconstitute an install of the web pages for the above cited FSX default scenery library objects:
https://web.archive.org/web/20210801230150/http://lc0277.gratisim.fr/sceneobjects.zip
Some of the other software for FSX by Lamont Clark (aka "LC0277") may also be of interest to you ...at this archive page:
https://web.archive.org/web/20210801235426/http://lc0277.gratisim.fr/software.html
It may work OK to use ADE for object placement with its limited "Bounding Box" base sizes for some purposes.
If you refer to the X, Y, size of the base length / width, and the Z size of the height (all in Meters) for the "Bounding Box" that surrounds a 3D model as stated in Lamont Clark's index pages extracted from the linked ZIP above, you may achieve your goal.
Be aware that "Bounding Boxes" are not always precisely the size of 3D object exterior surfaces; they are 'close' ...but larger.
Personally I would instead do this using Flight1's
Instant Scenery 3 (aka "IS3").
https://www.flight1.com/products.asp?product=iscen3
In Instant Scenery, one can manipulate the 3D scenery objects with the Mouse
or the Joystick, type in Altitude / Elevation as AMSL or AGL, display labels over objects to find out what their names are, and what scenery library files they are in etc..
Regarding challenges of maintaining a steady control of the 3D object when placing it via ADE GUI or IS3 if one has a tremor:
When connected to the user aircraft in FSX (ADE requires FSUIPC installed), set the FSX Simulation Rate to the slowest setting and position the user aircraft in Slew mode with the Numeric Keypad.
If using the Mouse to position the object via ADE GUI rather than via the user aircraft, instead of a desktop or other glossy smooth surface, you could try a coarse fabric woven surface MousePad with a Mouse that is small enough that your fingers can reach over its sides to contact / grip the MousePad surface.
Then ones Mouse movements may be moreso by the fingers and palm of the hand rather than by the wrist or forearm.
IIRC, when hand control is the site of greater difficulty rather than the wrist or forearm, IS3 can be switched from "Attach Object to Mouse cursor" mode into "Attach Object to user aircraft" mode, so that 3D object movement can be achieved by the limb using
ex: a joystick type game controller.
Alternatively, one can set the FSX Simulation Rate to the slowest setting and position the user aircraft in Slew mode with the Numeric Keypad.
You may also be interested in using Don Grovestine's SlewMaster utility:
https://www.google.com/url?q=http://stuff4fs.com/newpage.asp?Folder=SlewMaster&sa=U&ved=2ahUKEwiR56vkvo_5AhWkj4kEHQM_DacQFnoECAIQAg&usg=AOvVaw0KhX2Exu6P1-MaauSqE_Y4
"
Four slew speeds are available:
Fast 100' / 30m per click
Medium 10' / 3m
Slow 1' / 30cm
Nudge 0.1' / 3cm"
Another such "Slew" utility which has numerous features that I used starting back in FS9 days:
fswidgets.com
http://fswidgets.com/shop/product_info.php?cPath=30&products_id=43
Yet another "Slew" utility for FSX:
Control the current camera view and zoom as well as use the aircraft slew mode to move your aircraft exactly to the position you need it.
www.fs-flightcontrol.com
< Of incidental note for MSFS users reading this thread ...another fascinating "Slew" utility with 'other' features: >
https://github.com/Elephant42/FS_Tool
Thanks for sharing what you have here in prior years, and I hope this helps with your current / continued project.
GaryGB