[PTPhillip]

Yes, it does create a .ptxt file. However, you do have to make those subfolders inside of the Track Presets folder. The .ptxt files should then be saved/moved inside of those subfolders. Oh, another detail... Since "Save As Template" includes all tracks in the session, the session should only contain tracks that should be in the track preset prior to choosing "Save As Template". A different solution that might appeal more to your mentioned workflow is this:
-Select the track(s) in the large session that you want to use as a preset.
-Choose "Export Selected Tracks as New Session" from the File menu.
-Press OK in the resulting dialog.
-Choose your location (inside of a subfolder within Track Presets).
-In the Finder, change the extension of the session from .ptx to .ptxt.
-Voila!