The padding, depending on it's thickness, could easily change your span, thus affecting your ability to get the thumb out cleanly.
The glove going over your thumb will also change the size of your thumb, making it a difficult fit, but I suppose if your ball fits poorly enough already it may work.
The above mentioned things are two major components of fit so it's probably not a great idea. On the other hand, Pete Weber has used a "modified" golf glove...