I'd be interested in finding a method of creating a random-by-album playlist while maintaining random-by-track standard iTunes playback

Just make an intermediate playlist: one playlist that encompasses all of your iTunes music, and set that playlist to play random by album. And have the smart playlist point to the intermediate playlist.

I have several playlists that use the trick above for one reason or another. The great thing is, you can make the intermediate playlist smart too (for instance, all music added in the last year), or just a subset (for instance, all music that is fit to play in a car).

The best addition is a script to automatically re-fill the random-album playlist (I have this running every morning at 8:00):

tell application "iTunes"
	stop
	delete tracks of playlist "━━ De juiste mix ━━"
	delay 1
	playpause
end tell