All three of my Hawks are of the T1 version without SMURFs but have the vane cutaway etc. as mentioned.

I enclose two photos of the T45, actually Paul Dunkley's superb model which clearly show these fins.

You will have to research the dimensions yourself, but the essential aspect is that at full nose down stab travel (ac nose up) the fins are exactly in line with the stab LE.

I had a note from John Farley a few years ago, sums it up most succinctly:

more flap vane, more lift, more downwash, higher induced A of A over the stab., more back stick = tailplane stall !

Apparently , on one early Hawk test flight, this nose down pitch took the Hawk past the vertical, recovered after flap retraction. Jim Hawkins was the driver, sadly killed some years later in Hawk 100 G- loc case.