Well, got it to space! No mission report yet, because during a pre-deorbit inspection, Bill noticed that something was wrong with the orbiter...
But holy cow, figuring out the CoM and thrust vector issues made me appreciate the details of the actual STS flight plan. Finally had to give up on SRBs for now - using the thrust limiter to balance the thrust vector but keep a good TWR for the 40t payload was too tedious. So I cheated and used some LF boosters with gimballed engines, now I just have to get the hang of the flight profile, and set the priority correctly on the ET tanks so I don't have to pump fuel around mid flight.