Just from a modern day perspective...a gallon of aviation fuel is roughly 6lbs...85*6 is 510lbs. In Betty Jane we were around 6,500-7000lbs, that's 4000lbs under gross weight, give or take. But, a tailheavy airplane is a tail heavy airplane. The addition of the rear instrument package, seat structure and a 220lb (average weight) passenger could be considered a rear tank half full of gas. The airplane was completely stable. We didn't pull more than 4.5-5gs but never had any indication of instability or "snatch". The controls in a Mustang are balanced but mildly heavy, even being aggressive you can't yank the stick around like a Pitts Special. The stall, even an accelerated stall gives you a ton of warning and recovers with even slight release of back pressure. The Mustang also has a powerful trim system...once in cruise flight you can set it and fly basically hands off, particulary in smooth air. The only time you have to re-trim the airplane is during power changes. I understand the wartime warnings and SOP regarding the fuse tank and aft CG...but it boils down to how you fly the airplane and knowing the complete envelope. The policy of burning off the fuse tank first served it's purpose. The Merlin burns a gallon a minute in cruise and varies at climb power settings...roughly an hours worth of fuel, which would get them to altitude and pretty close to any combat area, where they could switch to the drops.
jim