If you raise the center of gravity by mounting armor plating up high, it makes a vehicle prone to rollovers at speeds over 35 mph.
"It also is questioning whether the handling and center of gravity in Humvees may have been altered by armor plating bolted on in Iraq or shields added around gun turrets."
This I can say from experience in driveing these things is the most likely cause of the rollovers.
If you raise the center of gravity by mounting armor plating up high, it makes a vehicle prone to rollovers at speeds over 35 mph.
It seems that by inserting a blank as compensating weight it would help in realigning the center of gravity. Any reduction in acceleration, top speed, or storage/passenger capacity would likely be an acceptable trade off. Sounds like these vehicles were 'redesigned' in the field and need some more tweaking.
Also, fear leads to over-correction in steering. Happens all the time around here stateside. Someone (usually a young driver) comes upon some debris on the interstate (usually a re-tread from a semi tire that they could drive over anyway) and they drastically yank the wheel one way, then back the other way and there you have it - roll over w/ tragic deaths.