Window tag with top/bottom elevation

For quite a few years we've had an ongoing discussion (among structural engineers) about how to best get the top and bottom of openings for windows, doors etc. out on a floor plan in Revit. I think the common ground has been to just enter text, or do a workaround with a spot elevation.

This is time consuming and bound for mishaps when we coordinate a project in 3d, but produce 2d drawings for the contractor where we override the information in the 3d model with text or maybe also a misplaced spot elevation. 

The following workflow probably is one of many solutions, and probably not the best either. I know that there are many ways to put a hole in a wall, each method with its own perks and flaws.
I'm going to use an "empty" window family to produce my openings, but I'm guessing the dynamo definition could be used for other openings as well.

Here is the definition:

(The GetTypeParameter.FrmFamilyInstance is a package found on the package manager and I think it's made by Peter Kompolschek.)

Before using this definition I have made two shared parameters called "Top window" and "Bottom window" which I imported into both the project parameters and the window tag.

Results:

If someone have a better idea for this, then let me know!

Here's a screencast video for the above. (and you have to excuse my overly affectionate mouse waving.. Jeezz..)