Slade,
i cant talk about the A-5 as all i am flying is and was the D-9. Tryed everything, but i still think, letting the auto manage your fuel is the best you can do.
On the D-9, the aft tank is already small - at least it feels like its far back in the fuselage. The auto almost empties it, then switches for the fwd for a while, turns back to the aft, then back to the fwd.
Emptying the aft tank first improves the stability in the stallfights, but makes the aircraft feel heavy, slowenings its reactions to the control inputs. Just like when a car is understeering. I dont need this on the D-9 because the plane is already steady as an arrow, but its more than a must in the 152.
Burning the fwd tank first is just a bad idea. The planes reactions to the inputs are much more violent, "i" cant aim properly. There is no 152-like control-loss habit, but the general feeling is pretty much the same. Post-stall moves became nearly impossible to be performed properly.
Leavning it on auto results the best balance "for my taste".