So tried the double Faust trick, and managed to get the 20 stam and 25 stam beaten.
I was close on the 30 stam final mission, and had I not gone away from the screen for a few moments I might have just pulled it off by using the Orchestra Melodies. The girls finished the map in 32 sec, and you need 29.99 to get the 30sec award. Funny enough this wasnt with double Faust build, but instead my own and a Red Gunner ally who had 44000 dmg, pretty much stripping half the HP bar of the boss with one ulty.

Also got two more copies yesterday, unbelievable as it sounds. So finally managed to max tap her into a Rainbow. Also, got another of the Red speed type equipment from the Tower maps, and managed to clear further on the Shadow Land missions getting me another copy of Faust in the process.
So overall pretty productive day in terms of Progress for GS
The Tier2 shadow Land missions give pretty nice EXP as well (22 per run, you get 10 runs per day) so after I hit a point where I am unable to progress further its a nice spot to grind for EXP and some of the Gold tier girls that can drop in those maps.