We lived in PMQs in Borden until last June, and they were far from full.  About 1/3 to 1/2 were empty, based on the unshovelled driveways, and emergency lights that were hanging in the front windows.  A friend was told that they had no more two-bedrooms, only three BRs, and all she was entitled to was a 2, so she was out of luck.  I personally could see about 7 empty 3 BRs from my kitchen window.
If you're a married/CL person, you should be able to get a 3 BR.  My friend was single, hence only entitled to a 2.
But yeah, the PAT situation is a tough slog.  From what I heard,  most of the married folks managed to eventually get their families to Borden if they wanted.  Seemed like every second person I met in the Qs was the spouse of a student at CFSATE!