@ appstro
you wrote "...I am referring to a Prepress level workflow".
So was I. This Illustrator file is exactly what they send to prepress - this is because the die is from a cad file, the die is opened in Adobe Illustrator by the designer, and the designer uses the die to build the design ON TOP OF SO IT FITS RIGHT - and they save it, and they send it to the prepress service provider.
Non Rampage users - notably Esko, Artworks Nexus users - they use a workflow that seems like a lot fewer steps than you are describing (with you InDesign / Rampage approach...)
They simply then drag that Illustrator file to a watched que to proof it (if they would like a hard copy proof) - as native Illustrator files can be set up to "contain" a full on PDF - or to place into some application (for muti-document pagination - or populate some job ticket (where they set it up to only make plates of the CMYK, spot color and the varnish - then either plot film for the foil and the emboss - or (if the company doing the foil stamping and embossing would prefer - they send them that same Illustrator file.
As I said, I have met a few that exchange PDF files for the same thing, but as designers sometimes do not really understand what a varnish plate has to be prepared - and once the prepress trains that designer - they get promoted or replaced - well, this is simply the ole "just send it to me the Illustrator file so i can edit and fix it" kind of thing...
I know VERY few people who place dies in InDesign in the first place - so, perhaps you are doing pop-up books that have dies AND pages ? Most people start and end in Illustrator when dealing with designing over a die.
Hope this helps !